Geological Time Scale Report - Technological University of the Philippines – Manila

Republic of the Philippines Technological University of the Philippines – Manila College of Engineering Department of Civil Engineering PCS2-M Professional Course- Specialized 2 Written Report Geological Time Scale Su...

Republic of the Philippines Technological University of the Philippines – Manila College of Engineering Department of Civil Engineering PCS2-M Professional Course- Specialized 2 Written Report Geological Time Scale Submitted by: Castillo, Dennise Rhea Deinla, Angelino De Guzman, Rose Hipolito, Mary Angeline N. Parena, Ben Rennil BSCE-4B Submitted to: Engr. Kevin M. Desales Date Submitted: September 16, 2024 I. INTRODUCTION Terminologies o Faunal succession: is the time arrangement of fossils in the geological record. o Formations: are stratigraphic successions containing rocks of related geological age that formed within the same geological setting. o Stratigraphic succession: is a sequence of layered sedimentary rocks and from root word stratigraphy. Stratigraphy: a branch of Geology and the Earth Sciences that deals with the arrangement and succession of strata, or layers, as well as the origin, composition and distribution of these geological strata o Ga: is an abbreviation used for billions (thousand million) of years ago. o Geochronology: is the study of the age of geological materials. o Ma: is an abbreviation used for millions of years ago. o Palaeobiology: is the study of the evolution of life during geologic time. o Palaeobotany: is the study of ancient plants. o Palaeontology: is the study of ancient lifeforms. Summary of history on measurement of GTS 1. The earliest geological time scales simply used the order of rocks laid down in a sedimentary rock sequence. 2. After Charles Darwin's publication Origin of Species (1859), was the fossilized remains of ancient animals and plants within the rock strata. (First generalized geological time scale.) 3. William Smith, he noted that different formations contained different fossils, and he could map one formation from another by the differences in the fossils which called temporal correlation. 4. Divisions in the geological time scales still use fossil evidence and mark major changes in the dominance of particular life forms. Differences between eons, era, periods, epochs and ages EONS The eon is the broadest category of geological time. Earth's history is characterized by four eons; in order from oldest to youngest, these are the Hadeon, Archean, Proterozoic, and Phanerozoic. Collectively, the Hadean, Archean, and Proterozoic are sometimes informally referred to as the "Precambrian." We live during the Phanerozoic, which means "visible life."  ERA Eons of geological time are subdivided into eras, which are the second-longest units of geological time. Most of our knowledge of the fossil record comes from the three eras of the Phanerozoic eon. The Paleozoic ("old life") era is characterized by trilobites, the first four-limbed vertebrates, and the origin of land plants. The Mesozoic ("middle life") era represents the "age of dinosaurs," the first appearances of mammals and flowering plants. The Cenozoic ("new life") era is sometimes called the "age of mammals" and is the era during which we live today. PERIODS Just as eons are subdivided into eras, eras are subdivided into units of time called periods. EPOCHS AND AGES Periods of geological time are subdivided into epochs. In turn, epochs are divided into even narrower units of time called ages. Geological Time Scale From root word "geology" which means study of the earth. It is based on the the geological rock record, which includes erosion, mountain building and other geological events. The geologic time scale is the “calendar” for events in Earth history. The enumeration of those geologic time units is based on stratigraphy, which is the correlation and classification of rock strata.  PRECAMBRIAN HADEAN EON Hadean Eon - the earliest eon of Precambrian time occurring between about 4.54 billion and about 4.0 billion years ago. It is characterized by Earth’s initial formation. Name after the Greek god and ruler of the underworld Hades. It was characterized by a partially molten surface, volcanism, and asteroid impacts Giant-Impact Hypothesis – a proto-planet now referred to as Theia, about the size of Mars, crashed into the Earth, and producing the tilt in Earth’s rotational axis in the process. Geodynamo: Because the solid inner core heats the outer liquid layer, it produces convection currents. This geodynamo is Earth’s magnetic field. Zircon crystals – the only surviving terrestrial material which are durable and can survive processes like subduction and weathering. The oldest minerals are the aforementioned grains of zircon, which were found in the Jack Hills of Australia. At the end of the Hadean Eon, the Earth was still in the late heavy bombardment stage. Asteroids and comets pelted Earth. ARCHEAN EON The word Archean is derived from the Greek word arkhē (αρχή), meaning 'beginning, origin'. EOARCHEAN ERA The Eoarchean era lasted from 4.0 Ga to 3.6 Ga and was the period of time when the Earth's crust solidified. During the Eoarchean the Earth began to cool. As the earth cooled, the area surrounding the Earth would cool as well. Condensation of the steam that had accumulated in the atmosphere from comets, and water vapor released through volcanism would create heavy rains which would fall to the Earth's surface accumulating to form our first shallow seas. At this time the atmosphere contained mostly carbon dioxide, nitrogen, and water vapor. There was no free oxygen in the atmosphere and you would not have been able to breath. PALEOARCHEAN ERA The Paleoarchean era lasted from 3.6 Ga to 3.2 Ga. The first evidence of life on Earth in the form of prokaryotic cells – anaerobic. The first photosynthetic organism utilizing anoxygenic (without oxygen) photosynthesis where the organism (bacteria or archaea) species use light energy and hydrogen sulfide instead of water to generate sulfur instead of oxygen. During the Paleoarchean there is evidence to suggest that Earth's first supercontinent may have been formed. This supercontinent is referred to as Vaalbara. MESOARCHEAN ERA The Mesoarchean era lasted from 3.2 Ga to 2.8 Ga and was the period of time during which the significant evolutionary radiation of microbial life. This advancement was one that enabled these initial prokaryotes to use light and carbon dioxide to produce sugars for food along with oxygen (oxygenic photosynthesis). These photosynthetic organisms were cyanobacteria. Cyanobacteria would introduce oxygen into our atmosphere that would eventually create our protective ozone in which organisms could live. Stromatolites – oldest fossils around 3.48 Ga which are rocky remnants of microbial mats formed by cyanobacteria living in tidal flats. Small supercontinent dates back to the Mesoarchean and is referred to as Ur. NEOARCHEAN ERA The Neoarchean era lasted from 2.8 Ga to 2.5 Ga. During this era, plate tectonics is now in full force. Studies completed by scientists show chemical changes in Neoarchean rocks which support the theory that about 3 billion years ago recycling of rocks had begun. Also, the presence of Neoarchean mafic and felsic rocks indicates rocks were being cycled and re-melted. Plate tectonics is a major player in many events in the future of Earth, starting now with the formation of our first "true" supercontinent during this era which has been named Kenorland. Banded Iron Formations (BIF) - are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iron-poor chert that range in age from 1.5 to 3.8 billion years old, the age of the earliest known rocks. PROTEROZOIC EON The word Proterozoic is derived from the combined two words of Greek origin: protero- meaning “former or earlier”, and -zoic meaning “of life”. PALEOPROTEROZOIC ERA The abundance of banded iron formations greatly increased during this time. The Great Oxidation Event occurred during this period also. Significant cooling of the planet and creation of the first snowball Earth. This is referred to as the Huronian glaciation event and it occurred 2.4 to 2.3 billion years ago. This major glaciation event was a consequence of the break up of Kenorland resulting in an immense spike in rainfall, which decreased greenhouse gasses, and caused the Earth to cool. Around two-billion years ago, following the disassociation of Kenorland another supercontinent would form called Nuna or Columbia. The eukaryotic cell was formed by cells consuming other cells. A eukaryotic cell has a membrane bound nucleus where DNA, or genes live and are the progenitors of protists, fungi, plants, and animals. MESOPROTEROZOIC ERA The supercontinent of Nuna/Columbia would break up during this era only to come back together to form the next supercontinent, Rodinia towards the very end of this era. Mesoproterozoic fossils show that the single celled eukaryotes, which evolved during the Paleoproterozoic, were living together as colonies or in slime aggregates. The cells would begin to communicate and take on specific functions (multicellular organism) Bangiomorpha pubescens - a species of red algae and is the first known sexually reproducing organism. NEOPROTEROZOIC ERA During the Neoproterozoic era, Rodinia would breakup and reassemble creating the next supercontinent Pannotia. The first putative metazoan (animal) fossils are the fossils of Otavia antiqua, which has been described as a primitive sponge by its discoverers and numerous other scholars, date back to about 800 Ma. The first large evolutionary radiation of acritarchs occurred during this period. Vase-shaped microfossils abound in Tonian sediments and represent the earliest testate amoebozoans. Due to the ongoing photosynthesis and large volcanic events were taking place, oxygen level had increased to 20% causing the Earth to cool down. This ice age would last about 120 million years and is the most extensive ice age that has taken place on planet Earth, so far. This mass glaciation event is often referred to as Snowball Earth.  Recognizable fossil evidence of life becomes common. Good fossils of multi-celled animals were found in Ediacaran sediments. The relatively sudden evolutionary radiation event, known as the Avalon Explosion, is represented by now-extinct, relatively simple soft-bodied animal phyla such as Proarticulata (bilaterians with simple articulation, e.g. Dickinsonia and Spriggina), Petalonamae (sea pen-like animals, e.g. Charnia), Aspidella (radial-shaped animals, e.g. Cyclomedusa) and Trilobozoa (animals with tri-radial symmetry, e.g. Tribrachidium).  PHANEROZOIC PALEOZOIC The Paleozoic Era, spanning from approximately 541 to 252 million years ago, represents one of the most significant periods in Earth’s history, often called the "Era of Ancient Life." It began with the Cambrian Explosion, a rapid diversification of life in the oceans, and ended with the largest mass extinction event Earth has ever seen. Over these nearly 300 million years, life evolved dramatically—from simple marine organisms to complex plants and animals capable of thriving on land. This era witnessed the appearance of the first fish, amphibians, reptiles, and land plants, marking the foundation of modern ecosystems. The continents also underwent significant changes, moving toward the formation of the supercontinent Pangea. The Paleozoic was a time of both growth and challenges, as the climate and landscapes shifted, and several extinction events reshaped life on Earth. The Devonian, Carboniferous, and Permian periods, in particular, were key stages in the development of vertebrates and terrestrial ecosystems, leading to the world as we know it today. Cambrian Period 1. Introduction o Purpose of the Report: This report explores the Cambrian Period, focusing on its geological and biological changes, and its significance in Earth's history. o Historical Context: The Cambrian Period is the first period of the Paleozoic Era, spanning from approximately 541 to 485.4 million years ago. It follows the Precambrian time and precedes the Ordovician Period. 2. Geological Characteristics 2.1. Plate Tectonics and Continental Configuration o Continental Arrangement: During the Cambrian, the continents were positioned differently from today. Most of the land was grouped into two supercontinents: Laurentia (which includes parts of North America) and Gondwana (which included Africa, South America, Australia, and Antarctica). The continents were arranged near the equator, resulting in diverse marine environments.  o Tectonic Activity: The period saw significant tectonic activity, including the breakup of the supercontinent Rodinia, which began around the end of the Precambrian. This breakup set the stage for the formation of the Cambrian continents. 2.2. Sea Levels and Climate o High Sea Levels: Cambrian sea levels were high, leading to the flooding of many continental areas. This created extensive shallow seas, which were ideal habitats for marine life. o Example: Large parts of the continents were covered by shallow seas, forming extensive epeiric seas. o Climate: The climate during the Cambrian was generally warm, with little evidence of glaciation. This warm climate helped support a wide range of marine life. 2.3. Sedimentary Deposits o Rock Formations: The Cambrian Period is characterized by the deposition of sedimentary rocks, including sandstone, shale, and limestone. The extensive limestone deposits are particularly important due to their association with the early development of marine ecosystems. 3. Biological Developments 3.1. Marine Life o Cambrian Explosion: One of the most significant events of the Cambrian Period was the "Cambrian Explosion," a rapid diversification of life forms. This period saw the emergence of many major groups of animals, leading to a dramatic increase in the complexity of life. o Trilobites: Trilobites were among the most prominent marine arthropods of the Cambrian Period. They were widespread and diverse, with various forms and sizes. o Examples: Paradoxides and Olenellus are notable trilobites from the Cambrian.  Paradoxides and Olenellus o Early Mollusks: The Cambrian Period saw the appearance of early mollusks, including ancestors of modern snails, clams, and cephalopods. o Examples: Anomalocaris (a large, early predator) and Hallucigenia (a strange, worm-like creature) are important Cambrian mollusks. Anomalocaris and Hallucigenia o Early Chordates: The Cambrian also saw the first chordates, which are animals with a notochord (a flexible rod-like structure). These early chordates are the ancestors of vertebrates. o Examples: Pikaia is an early chordate known from Cambrian fossils. Pikaia o Brachiopods: Brachiopods were abundant and diverse, with many new species evolving during this period. o Examples: Lingula and Crania are representative brachiopods from the Cambrian. Lingula and Crania  3.2. Evolutionary Significance o Development of Hard Parts: Many Cambrian organisms developed hard shells and exoskeletons, which helped in their preservation as fossils. This development marked a significant evolutionary advance. o Ecosystem Complexity: The Cambrian Explosion led to the creation of complex marine ecosystems with various predator-prey relationships and ecological interactions. 4. Significance of the Cambrian Period o The Cambrian Explosion: This period is significant for the dramatic increase in the diversity of life forms, which laid the groundwork for future evolutionary developments. o Foundation of Marine Ecosystems: The Cambrian Period established many of the fundamental marine ecosystems and animal phyla that would continue to evolve throughout the Paleozoic and beyond. Conclusion The Cambrian Period was a time of extraordinary change and development. The "Cambrian Explosion" led to a rapid increase in the diversity and complexity of life forms, setting the stage for the evolution of modern ecosystems. The period’s high sea levels, warm climate, and extensive sedimentary deposits provide a crucial window into the early history of life on Earth. Ordovician Period 1. Introduction o Purpose of the Report: This report provides an in-depth examination of the Ordovician Period, focusing on its geological and biological changes and their impact on Earth’s history. o Historical Context: The Ordovician Period is part of the Paleozoic Era, spanning from approximately 485.4 to 443.8 million years ago. It follows the Cambrian Period and precedes the Silurian Period. 2. Geological Characteristics 2.1. Plate Tectonics and Continental Configuration o Continental Arrangement: During the Ordovician, the continents were positioned differently from today. Gondwana, a supercontinent, was located near the South Pole, while other landmasses like Laurentia (which would become North America) and Baltica (which would become part of Europe) were closer to the equator. This arrangement led to the development of various marine environments and tectonic activities. o Tectonic Activity: The period experienced significant tectonic activity, including the formation of  mountain ranges due to collisions between continental plates. One notable event was the beginning of the Taconic Orogeny, a mountain-building episode in what is now eastern North America. 2.2. Sea Levels and Climate o High Sea Levels: The Ordovician Period was characterized by high sea levels, which led to extensive shallow seas covering much of the continents. This created vast marine environments rich in life. o Climate: The climate was generally warm and stable, with minimal glaciation. However, towards the end of the period, a significant cooling event occurred, leading to the first major ice age of the Paleozoic Era. 2.3. Sedimentary Deposits o Rock Formations: The period is marked by the deposition of various sedimentary rocks, including limestone, sandstone, and shale. Limestone deposits, in particular, are prominent due to the extensive growth of marine life and the formation of large coral reefs. 3. Biological Developments 3.1. Marine Life o Marine Biodiversity: The Ordovician Period is noted for its explosion in marine biodiversity, often referred to as the “Ordovician Radiation.” This event led to the diversification of many marine groups. o Coral Reefs: Coral reefs became widespread and were composed mainly of tabulate and rugose corals. These reefs formed complex structures that provided habitats for numerous marine organisms. o Examples: Favosites (a tabulate coral) and Halysites (a tabulate coral) are examples of Silurian corals found in Ordovician reefs.  Favosites Halysites o Trilobites: Trilobites were among the dominant marine arthropods. They continued to diversify, with many new genera and species appearing during this period. o Examples: Dalmanites and Isotelus are notable trilobites from the Ordovician. Dalmanella Isotelus o Brachiopods: These marine invertebrates were highly diverse, with many new species evolving during this time. o Examples: Orthotheca and Rhabdophora are examples of Ordovician brachiopods. Orthotheca Rhabdophora o Early Vertebrates: The Ordovician Period also saw the appearance of the first jawless fish, known as agnathans. These early vertebrates were an important step in the evolution of more complex fish. o Examples: Pteraspis and Cephalaspis are examples of early jawless fish.  Pteraspis Cephalaspis 3.2. Terrestrial Life o First Land Plants: The Ordovician saw the emergence of the earliest land plants, which were simple, non-vascular plants. These early plants were small and likely grew in moist environments. o Examples: Cooksonia, one of the earliest vascular plants, began to appear towards the end of the Ordovician. Cooksonia o Fungi: Evidence suggests that fungi also began to colonize land during this period, playing a role in breaking down organic material and forming soil. 4. Extinction Events o End-Ordovician Extinction: The period ended with one of the largest mass extinctions in Earth’s history, known as the End-Ordovician extinction. This event was likely caused by a short, intense ice age, leading to significant drops in sea levels and changes in climate. o Impact: The extinction event led to the loss of approximately 60% of marine species, including many trilobites, brachiopods, and corals.  5. Significance of the Ordovician Period o Evolutionary Milestones: The Ordovician Period was crucial for the diversification of marine life and the early evolution of vertebrates. The period’s marine ecosystems set the stage for further evolutionary developments in the subsequent periods. o Geological and Climatic Changes: The high sea levels, extensive reef-building, and climatic shifts during the Ordovician Period had a lasting impact on Earth’s geological and biological history. Conclusion The Ordovician Period was a time of remarkable change and development. From the explosion of marine life and the formation of vast coral reefs to the early colonization of land by plants and fungi, the Ordovician laid important foundations for future evolutionary and ecological developments. The period ended with a significant extinction event, marking a dramatic shift in Earth’s history. Silurian Period 1. Introduction o Purpose of the Report: This report aims to provide a detailed examination of the Silurian Period, focusing on its geological and biological changes and their implications for Earth’s history. o Historical Context: The Silurian Period is part of the Paleozoic Era, which spans from approximately 443.8 to 419.2 million years ago. The Silurian follows the Ordovician Period and precedes the Devonian Period. 2. Geological Characteristics 2.1. Plate Tectonics and Continental Configuration o Continental Drift: During the Silurian Period, the positions of the continents were significantly different from today. Laurentia (which would become North America) and Baltica (which would become part of Europe) began to collide, forming the Caledonian Orogeny. This collision led to the creation of the Caledonian Mountains, extending through parts of Scotland, Scandinavia, and eastern North America. o Supercontinent Gondwana: Gondwana was situated near the South Pole, encompassing what is now Africa, South America, Australia, and Antarctica. Other landmasses, such as Laurentia and Baltica, were closer to the equator. 2.2. Sea Levels and Climate o High Sea Levels: The Silurian Period experienced high sea levels, resulting in extensive shallow seas. These conditions created ideal environments for marine life and the development of coral reefs. o Warm Climate: The climate was generally warm with little to no glaciation, promoting the expansion of both marine and terrestrial habitats. 2.3. Sedimentary Deposits o Rock Formations: Major sedimentary rocks from the Silurian Period include limestone, sandstone, and shale. The extensive limestone deposits were particularly significant due to the proliferation of coral reefs and marine life. 3. Biological Developments 3.1. Marine Life o Coral Reefs: The Silurian Period saw the development of extensive coral reefs dominated by tabulate and rugose corals. These reefs supported diverse marine ecosystems. o Examples: Favosites (a tabulate coral) and Halysites (another tabulate coral) are representative of Silurian coral reefs. Favosites Halysites o Trilobites: Trilobites were still a major component of marine fauna, with both continued diversification and some decline in certain genera. o Examples: Dalmanites and Proetus are notable Silurian trilobites.  Dalmanites Proetus o Brachiopods: These marine invertebrates remained diverse, with several new species evolving. o Examples: Dalmanella and Syringothyris are significant Silurian brachiopods. Dalmanella Syringothyris o Early Jawed Fish: The appearance of jawed fish marked a major evolutionary advancement. The first true jawed vertebrates, known as placoderms, emerged during this period. o Examples: Pteraspis (an early jawless fish) and the early placoderms are important representatives. Pteraspis 3.2. Terrestrial Life o Early Land Plants: The Silurian Period witnessed the rise of early vascular plants, which played a crucial role in colonizing terrestrial environments. o Examples: Cooksonia is one of the earliest known vascular plants from this period. Cooksonia o Non-Vascular Plants: Liverworts and mosses also began to colonize land, contributing to the development of early terrestrial ecosystems. 3.3. Arthropods o Early Arachnids: The period saw the emergence of early arachnids. o Example: Pernops is an early arachnid known from the Silurian. o Myriapods: The ancestors of millipedes and centipedes appeared during this time, marking the early stages of terrestrial arthropod evolution. 4. Significance of the Silurian Period o Evolutionary Advances: The Silurian Period was significant for the evolution of jawed vertebrates and the early colonization of land by plants and arthropods. The development of jawed fish represents a key evolutionary milestone.  o Ecological Development: The expansion of coral reefs and the diversification of marine and terrestrial life underscore the period’s importance in shaping Earth’s biological history. Conclusion The Silurian Period was a dynamic time of geological and biological transformation. The period’s warm climate and high sea levels facilitated the development of diverse marine ecosystems and allowed for the initial colonization of land by plants and arthropods. The evolutionary advancements during this time laid important groundwork for future developments in Earth’s history. Devonian Period (419 to 359 million years ago) Summary: o The Devonian Period, often called the "Age of Fishes," was a transformative time for life on Earth. It witnessed the great diversification of fish, including the rise of jawless fish, placoderms (armored fish), early sharks, and the ancestors of amphibians. Notably, this period also marked the first significant colonization of land by plants and animals. The evolution of lobe-finned fish into tetrapods was a key step in this process, leading to the first land-dwelling vertebrates. Additionally, the first true forests appeared, transforming the Earth’s landscape and atmosphere. The period ended with a significant extinction event, which drastically reduced marine biodiversity, particularly affecting coral reefs. Key Developments: o Explosion of Fish Diversity: Fish species thrived, and some developed jaws and strong, bony fins. Placoderms, like the Dunkleosteus, a giant armored fish up to 10 meters long, were the apex predators of the Devonian seas. o First Land Vertebrates: Lobe-finned fish, such as Eusthenopteron, are often considered key transitional species. Their descendants, like Tiktaalik, possessed both gills and primitive lungs, allowing them to breathe air and move onto land. o Development of Forests: Early vascular plants, including Archaeopteris, were the first large trees, forming Earth's earliest forests and playing a critical role in stabilizing atmospheric oxygen levels. These forests also provided habitats for a wide range of insects and early land- dwelling animals. o Late Devonian Extinction: Occurring around 375 million years ago, this extinction event wiped out about 70% of marine species, severely impacting coral reefs and many fish species. It's thought that rapid environmental changes, possibly triggered by volcanic activity, were responsible for this crisis. Geological and Climate Aspects: o Shallow Seas: Much of the planet was covered by warm, shallow seas, which supported coral reefs, crinoids (sea lilies), and trilobites. The Devonian also saw extensive reef-building by stromatoporoids and tabulate corals. o Climate: The global climate was generally warm, but there were fluctuations in sea levels and possible cooling periods towards the end of the Devonian, which may have contributed to the extinction event.  Additional Details: o The first seed-bearing plants (gymnosperms) appeared during this period, allowing plants to reproduce without needing water for fertilization, a crucial step in the spread of life across dry land. o Fossils of Ichthyostega, an early tetrapod, show a mix of fish-like and amphibian features, representing one of the earliest known land animals. Carboniferous Period (359 to 299 million years ago) Summary: o The Carboniferous Period, known for its vast swampy forests, gave rise to the immense coal deposits we mine today. During this time, Earth's atmosphere had extremely high levels of oxygen, which allowed insects and amphibians to grow to enormous sizes. This period also saw the rise of the first true reptiles, with the development of the amniotic egg, allowing them to lay eggs on land without relying on water. The Carboniferous is split into two sub-periods: the Mississippian (early) and the Pennsylvanian (late), each characterized by different climates and environments. Key Developments: o Coal Swamps: Dense, humid forests of giant club mosses, ferns, and horsetails (such as Lepidodendron and Sigillaria) covered much of the planet, creating the conditions for vast coal deposits. Over millions of years, dead plant material from these forests was buried and compacted, forming the coal that is still mined today. o Giant Insects: The high oxygen levels of this period allowed for the evolution of giant insects, such as the Meganeura, a dragonfly with a wingspan of over 2 feet (60 cm), and Arthropleura, a millipede-like creature that could grow up to 2.5 meters (8 feet) long. o Evolution of Amniotes: Early reptiles, like Hylonomus, evolved the amniotic egg, which had a protective shell and membrane, allowing these animals to reproduce on land. This adaptation freed them from having to lay eggs in water, like amphibians. Geological and Climate Aspects: o Tropical Swamps: Large parts of the world, especially in equatorial regions, were dominated by vast swamp forests. These areas were warm, wet, and ideal for the lush plant growth that created the coal beds we use today. o Ice Ages: During the later part of the Carboniferous, the planet entered an ice age, with glaciers forming at the poles. This cooling trend affected global sea levels and climates. Additional Details: o The Carboniferous Rainforest Collapse occurred towards the end of this period, when a shift in climate caused the collapse of vast tropical forests. This change led to the extinction of many amphibians but allowed reptiles to thrive in the drier conditions. o Fossil evidence from this period includes well-preserved remains of giant insects and amphibians, as well as Glossopteris and other ancient plants found in coal seams. Permian Period (299 to 252 million years ago) Summary: o The Permian Period was a time of significant change, both in terms of climate and life. It saw the dominance of reptiles, particularly the synapsids, early relatives of mammals. The continents gradually merged into the supercontinent Pangea, dramatically altering the global climate, with vast deserts forming in the interior. The Permian ended with the most devastating mass extinction in Earth's history, known as "The Great Dying," which wiped out nearly all marine and land species, paving the way for the rise of dinosaurs in the Mesozoic Era. Key Developments: o Rise of Synapsids: Early synapsids, like Dimetrodon (often mistaken for a dinosaur), became dominant. These "mammal-like reptiles" had specialized teeth and are considered ancestors of modern mammals. Another synapsid, Gorgonops, was a top predator during the Permian. o Evolution of Therapsids: Therapsids, more advanced mammal-like reptiles, emerged in the later part of the Permian, showing features closer to modern mammals, including differentiated teeth and possibly hair. o Permian Extinction: The end of the Permian Period marked the largest extinction event in Earth’s history. Nearly 90% of marine species, including trilobites and many fish, and 70% of land species, including many reptiles and plants, were wiped out. Volcanic eruptions in the Siberian Traps are considered a leading cause, releasing vast amounts of greenhouse gases into the atmosphere and triggering global warming and ocean acidification. Geological and Climate Aspects: o Formation of Pangea: The merging of Earth's landmasses into Pangea led to extreme climate conditions. The interior of the supercontinent became dry and arid, while coastal areas had more moderate climates. This shift led to a reduction in shallow marine environments, which were crucial for marine biodiversity. o Drying Climate: As Pangea formed, deserts spread across the interior, drastically reducing moisture levels. This made survival harder for many plants and animals adapted to more humid environments. Additional Details: o End-Permian Extinction: The Permian-Triassic Extinction Event, often referred to as "The Great Dying," is thought to have been caused by massive volcanic eruptions, climate change, and a drop in oxygen levels in the oceans. It took millions of years for life to recover after this event. o Fossils from the Permian, like those of the Lystrosaurus, a therapsid that survived the extinction, give clues about how some species adapted to the changing conditions.  MESOZOIC The Mesozoic Era (251.9 to 66.0 million years ago) was the "Age of Reptiles." Mesozoic Era, second of Earth’s three major geologic eras of Phanerozoic time. Its name is derived from the Greek term for “middle life.” The Mesozoic Era began 251.9 million years ago, following the conclusion of the Paleozoic Era, and ended 66 million years ago, at the dawn of the Cenozoic Era. The major divisions of the Mesozoic Era are, from oldest to youngest, the Triassic Period, the Jurassic Period, and the Cretaceous Period. Earth’s climate during the Mesozoic Era was generally warm, and there was less difference in temperature between equatorial and polar latitudes than there is today. The Mesozoic was a time of geologic and biological transition. During this era the continents began to move into their present-day configurations Mesozoic Time Periods Triassic Period in geologic time, the first period of the Mesozoic Era. It began 252 million years ago, at the close of the Permian Period, and ended 201 million years ago, when it was succeeded by the Jurassic Period. The Triassic Period marked the beginning of major changes that were to take place throughout the Mesozoic Era, particularly in the distribution of continents, the evolution of life, and the geographic distribution of living things. At the beginning of the Triassic, virtually all the major landmasses of the world were collected into the supercontinent of Pangea. Terrestrial climates were predominately warm and dry (though seasonal monsoons occurred over large areas), and the Earth’s crust was relatively quiescent. At the end of the Triassic, however, plate tectonic activity picked up, and a period of continental rifting began. On the margins of the continents, shallow seas, which had dwindled in area at the end of the Permian, became more extensive; as sea levels gradually rose, the waters of continental shelves were colonized for the first time by large marine reptiles and reef-building corals of modern aspect. The Triassic followed on the heels of the largest mass extinction event in the history of the Earth. This event occurred at the end of the Permian, when 85 to 95 percent of marine invertebrate species and 70 percent of terrestrial vertebrate genera died out. Theory of this mass extinction event: Oceanic anoxia (lack of dissolved oxygen) in both low and high latitudes over a wide range of shelf depths, perhaps caused by weakening of oceanic circulation. Such anoxia could devastate marine life, particularly the bottom-dwellers (benthos). Any theory, however, must take into account that not all groups were affected to the same extent by the extinctions. As a result, Early Triassic biotas were impoverished, though diversity and abundance progressively increased during Middle and Late Triassic times. The fossils of many Early Triassic life-forms tend to be Paleozoic in aspect, whereas those of the Middle and Late Triassic are decidedly Mesozoic in appearance and are clearly the precursors of things to come. New land vertebrates appeared throughout the Triassic. By the end of the period, both the first true mammals and the earliest dinosaurs had appeared. During the recovery of life in the Triassic Period, the relative importance of land animals grew. Reptiles increased in diversity and number, and the first dinosaurs appeared, heralding the great radiation that would characterize this group during the Jurassic and Cretaceous periods. Finally, the end of the Triassic saw the appearance of the first mammals—tiny, fur-bearing, shrewlike animals derived from reptiles. One of the earliest true mammals was the three-foot-long (one-meter-long) Eozostrodon. The shrewlike creature laid eggs but fed its young mother's milk. Among the first dinosaurs was the two-  footed carnivore Coelophysis, which grew up to 9 feet (2.7 meters) tall, weighed up to a hundred pounds (45 kilograms), and probably fed on small reptiles and amphibians. Another episode of mass extinction occurred at the end of the Triassic. Though this event was less devastating than its counterpart at the end of the Permian, it did result in drastic reductions of some living populations—particularly of the ammonoids. Intense volcanic activity associated with the breakup of Pangea is thought to have raised carbon dioxide levels in the atmosphere and increased the acidity of the oceans. Since this volcanism coincided with the beginning of the end-Triassic extinction, it is considered by many paleontologists to be the extinction’s most likely cause. Jurassic Period Jurassic Period, second of three periods of the Mesozoic Era. Extending from 201.3 million to 145 million years ago. During this period the supercontinent Pangea split apart, allowing for the eventual development of what are now the central Atlantic Ocean and the Gulf of Mexico. Heightened plate tectonic movement led to significant volcanic activity, mountain-building events, and attachment of islands onto continents. Rock strata laid down during the Jurassic Period have yielded gold, coal, petroleum, and other natural resources. Records of sea level changes can be found on every continent. Because there is no evidence of major glaciations in the Jurassic, any global sea level change must have been due to thermal expansion of seawater or plate tectonic activity (such as major activity at seafloor ridges). Some geologists have proposed that average sea levels increased from Early to Late Jurassic time. Analyses of oxygen isotopes in marine fossils suggest that Jurassic global temperatures were generally quite warm. Geochemical evidence suggests that surface waters in the low latitudes were about 20 °C (68 °F), while deep waters were about 17 °C (63 °F). Coolest temperatures existed during the Middle Jurassic and warmest temperatures in the Late Jurassic. A drop in temperatures occurred at the Jurassic- Cretaceous boundary. It has been suggested that increased volcanic and seafloor-spreading activity during the Jurassic released large amounts of carbon dioxide—a greenhouse gas—and led to higher global temperatures. Ocean circulation was probably fairly sluggish because of the warm temperatures, lack of ocean density gradients, and decreased winds. As stated above, there is no evidence of glaciation or polar ice caps in the Jurassic. This may have been caused by the lack of a continental landmass in a polar position or by generally warm conditions; however, because of the complex relationships between temperature, geographic configurations, and glaciations, it is difficult to state a definite cause and effect. During the Early Jurassic, animals and plants living both on land and in the seas recovered from one of the largest mass extinctions in Earth history. Many groups of vertebrate and invertebrate organisms important in the modern world made their first appearance during the Jurassic. Life was especially diverse in the oceans—thriving reef ecosystems, shallow-water invertebrate communities, and large swimming predators, including reptiles and squidlike animals. On land, dinosaurs and flying pterosaurs dominated the ecosystems, and birds made their first appearance. Early mammals also were present, though they were still fairly insignificant. Insect populations were diverse, and plants were dominated by the gymnosperms, or “naked-seed” plants. Cretaceous Period Cretaceous Period, in geologic time, the last of the three periods of the Mesozoic Era. The Cretaceous began 145.0 million years ago and ended 66 million years ago. The Cretaceous is the longest period of the Phanerozoic Eon. Spanning 79 million years, it represents more time than has elapsed since the extinction of the dinosaurs, which occurred at the end of the period. The Cretaceous Period began with Earth’s land assembled essentially into two continents, Laurasia  in the north and Gondwana in the south. These were almost completely separated by the equatorial Tethys seaway, and the various segments of Laurasia and Gondwana had already started to rift apart. When the Cretaceous Period ended, most of the present-day continents were separated from each other by expanses of water such as the North and South Atlantic Ocean. At the end of the period, India was adrift in the Indian Ocean, and Australia was still connected to Antarctica. Sea level was higher during most of the Cretaceous than at any other time in Earth history, and it was a major factor influencing the paleogeography of the period. In general, world oceans were about 100 to 200 metres (330 to 660 feet) higher in the Early Cretaceous and roughly 200 to 250 metres (660 to 820 feet) higher in the Late Cretaceous than at present. The high Cretaceous sea level is thought to have been primarily the result of water in the ocean basins being displaced by the enlargement of midoceanic ridges. The climate was generally warmer and more humid than today, probably because of very active volcanism associated with unusually high rates of seafloor spreading. The polar regions were free of continental ice sheets, their land instead covered by forest. Dinosaurs roamed Antarctica, even with its long winter night. Temperatures were lower at the beginning of the period, rising to a maximum in the mid- Cretaceous and then declining slightly with time until a more accentuated cooling during the last two ages of the period. Ice sheets and glaciers were almost entirely absent except in the high mountains, so, although the end of the Cretaceous was coolest, it was still much warmer than it is today The lengthy Cretaceous Period constitutes a major portion of the interval between ancient life-forms and those that dominate Earth today. Dinosaurs were the dominant group of land animals, especially “duck- billed” dinosaurs (hadrosaurs), such as Shantungosaurus, and horned forms, such as Triceratops. Giant marine reptiles such as ichthyosaurs, mosasaurs, and plesiosaurs were common in the seas, and flying reptiles (pterosaurs) dominated the sky. Flowering plants (angiosperms) arose close to the beginning of the Cretaceous and became more abundant as the period progressed. At or very close to the end of the Cretaceous Period, many animals that were important elements of the Mesozoic world became extinct. On land the dinosaurs perished, but plant life was less affected. that the impact of an asteroid on Earth may have triggered the extinction event by ejecting a huge quantity of rock debris into the atmosphere, enshrouding Earth in darkness for several months or longer. With no sunlight able to penetrate this global dust cloud, photosynthesis ceased, resulting in the death of green plants and the disruption of the food chain. Mesozoic Geology Mesozoic rocks are widely distributed, appearing in various parts of the world. A large percentage of these rocks are sedimentary. At various times during the Mesozoic, shallow seas invaded continental interiors and then drained away. Seas again transgressed upon the continents between the Early and Late Jurassic and in the Early Cretaceous, leaving extensive beds of sandstone, ironstone, clays, and limestone. Marine transgression was so extensive that in North America, for example, a seaway spread all the way from the Arctic to the Gulf of Mexico in the Cretaceous Period. Widespread deposition of chalk, clay, black shales, and marl occurred. In parts of North America, lake and river sediments rich in dinosaur fossils were deposited alongside marine sediments. A substantial amount of igneous rock also formed during the Mesozoic. Two of the largest volcanic events in Earth’s history occurred during the Mesozoic. The Central Atlantic Magmatic Province, a huge volume of basalt, was created at the end of the Triassic during the initial rifting of Pangea. The surface area of this igneous province originally covered more than 7 million square km (about 3 million square miles), and its rocks can be found today from Brazil to France. Despite such a massive volume of basaltic material extruded, volcanic activity was probably short-lived, spanning only a few million years. At the end of the Cretaceous, another igneous province, the flood basalts of the Deccan Traps, formed on what is now the Indian subcontinent.  Cenozoic The term Cenozoic, originally spelled Kainozoic, was introduced by English geologist John Phillips in an 1840. Quaternary It is famous for the many cycles of glacial growth and retreat, the extinction of many species of large mammals and birds, and the spread of humans. Holocene Marked climatic warming and the disappearance of the continental glaciers. The extinction of megafauna (large animals) such as mammoths, mastodons, giant ground sloths, saber-toothed cats, and short-faced bears Pleistocene Popularly known as the “Ice Age”. The resultant land bridge permitted animals to move between the two continents, including the dispersal of the first humans into the Americas. Modern humans including Homo erectus, H. neanderthalensis and H. sapiens evolved Neogene It started with the replacement of vast areas of forest by grasslands and savannahs. Complex patterns of mammalian evolution resulted from changing climates and continental separations. More modern mammals evolved as grasslands became widespread and the climate cooled and dried. The dramatic cooling phases of the Neogene lead to more distinctive latitudinal biotic zones. The term Neogene comes from the grouping by Hornes (1853) of the Miocene, the Pliocene and the Pleistocene into the “Neogen Stufe.” Pliocene The catastrophic filling of the Mediterranean Sea. The collisions of the African and Eurasian continents during the Miocene had closed the Mediterranean basin both in the east and at the Straits of Gibraltar resulting in the basin drying up and converting to grasslands the Panamanian bridge was formed between North and South America allowing for the migration of animals both north and south in what is known as the “Great American Faunal Interchange.” o Giant ground sloths, armadillos, and marsupials among others came north, while cats, dogs, bears, camels, and others went south In Africa early hominids appear for the first time in the fossil record. (Famous hominid fossils such as "Lucy" a female Australopithecus aferensis). Miocene The new circulation patterns in turn lead to the evolution and spread of diverse marine mammals including a variety of toothed and baleen whales, sea lions, seals, walruses and sea cows. Non-mammalian predators included marine crocodiles and the largest known shark, Carcharodon megalodon. Marine invertebrates were similar to today, in fact half of the species are unchanged. The variety of mammals that evolved to occupy the grasslands and savannahs of North America in the Miocene epoch: o Perrisodactyl Moropus, a clawed herbivore related to horses, confronting Daphoenodon dogs. o A foreground is a herd of extinct horses, Parahippus, that was evolving from a browsing habit to a grazing (eating grass) one. o A group of semiaquatic Promerycochoerus and a Daeodon, a large (12 ft long) pig-like scavenger or predator. Paleogene On land primitive mammals and birds began to spread rapidly. In the seas planktonic foraminifera and nanofossils begin new evolutionary paths. Most marine life resembles modern forms: the wonder of Cenozoic fossils is seeing recognizable organisms cast in stone, rather than the exotic, 'alien' life forms, such as sea lilies, ammonoids, and trilobites, of the Mesozoic and Paleozoic Eras. The term Paleogene is from Naumen’s “Paleogen Stufe” (1866) in which he combined the Eocene and the Oligocene. Oligocene The global cooling that eventually leads to later ice ages begins during this epoch. Forests begin to shrink and grasslands expand at the expense of forests. The two suborders of whales alive today, the toothed and baleen whales evolved. South America breaks away from Antarctic, allowing an isolating circum-antarctic current and a permanent ice cap to form, lowering world temperatures. Eocene Begins with extreme Global warming, the warmest five million years of the Cenozoic. This warming was probably due to a large methane release from the ocean floor. The first odd-toed mammals (perissodactyls, such as rhinos and horses) and even-toed mammals (artiodactyls such as camels) were present at the beginning of the epoch. The first marine mammals, including the first whales, appear in the seas, and the first primates appear on land. Africa is now an island continent. The climate began the long cooling trend that would continue through the Cenozoic in the middle of the Eocene. Paleocene Small mammals and birds diversify in dense forests as Earth recovers from the (K-T) extinction. The loss of the giant reptiles that dominated the Mesozoic Era left the world. The diverse mammalian fauna remained small. Deciduous trees dominated swamp forests in North America from middle latitudes to the Arctic ocean. Insect herbivory finally recovered from the K-T extinction event in the late Paleogene, nine million years after the event. In the oceans, most reptiles vanished, turtles and crocodilians being exceptions. Sharks and teleost fish become more common, and bony fishes dominate the seas as they will continue to do to the present day.  Among invertebrates more modern forms of gastropods and bivalves, foraminiferans and echinoids appear. As a result of various geological events like the island continent of India colliding with Asia, there was a rapid worldwide rise in temperature at the end of the epoch. REFERENCES: A Blast From The Past. Dinopedia. https://dinopedia.fandom.com/wiki/Ediacaran Hadean Eon: The Formation of Earth (4.6 to 4.0 billion years ago. EarthHow. https://earthhow.com/hadean-eon/ Proterozoic Eon: Eukaryotes to Multicellular Life (2500 to 541 million years ago). EarthHow. https://earthhow.com/proterozoic-eon/ The Geologic Time Application. ArcGIS Online. https://experience.arcgis.com/experience/397d0992c69e447c826af8069838a378/page/Hadean/?views= mA--Paleogeography%2Cn%E1%82%B2---Resources What Happened in the Archean Eon? [4.0 to 2.5 billion years ago]. EarthHow. https://earthhow.com/archean-eon/ Harper, D. A. T. (Year). The Paleozoic Era: The Silurian Period. Publisher. Martin, E. N. K. E. L. W. K. (Year). Invertebrate Paleontology and Evolution. Publisher. "Silurian Coral Reefs: New Insights from a Newly Discovered Outcrop" - Journal of Paleontology. "The Evolution of Early Jawed Vertebrates during the Silurian Period" - Palaeontology. The Paleobiology Database University of California Museum of Paleontology - Silurian Period Smithsonian National Museum of Natural History - Fossil History "The Cambrian Explosion: The Construction of Animal Diversity" by D. A. T. Harper "Invertebrate Paleontology and Evolution" by E. N. K. E. L. W. K. Martin "Cambrian Marine Ecosystems: New Insights from Recent Discoveries" - Journal of Paleontology "The Evolutionary Significance of the Cambrian Explosion" - Palaeontology The Paleobiology Database University of California Museum of Paleontology - Cambrian Period Smithsonian National Museum of Natural History - Fossil History "The Paleozoic Era: The Ordovician Period" by D. A. T. Harper "Invertebrate Paleontology and Evolution" by E. N. K. E. L. W. K. Martin "Ordovician Coral Reefs: New Insights from Recent Discoveries" - Journal of Paleontology "The Evolution of Early Vertebrates during the Ordovician Period" - Palaeontology The Paleobiology Database University of California Museum of Paleontology - Ordovician Period Smithsonian National Museum of Natural History - Fossil History Benton, M.J. (2005). When Life Nearly Died: The Greatest Mass Extinction of All Time. Thames & Hudson. Prothero, D.R. (1998). Bringing Fossils to Life: An Introduction to Paleobiology. McGraw-Hill. Stanley, S.M. (1999). Earth System History. W.H. Freeman and Company. Tang, C. Marie (2024, August 28). Mesozoic Era. Encyclopedia Britannica. https://www.britannica.com/science/Mesozoic-Era Logan, A. (2024, August 21). Triassic Period. Encyclopedia Britannica. https://www.britannica.com/science/Triassic-Period Tang, C. Marie (2024, August 9). Jurassic Period. Encyclopedia Britannica. https://www.britannica.com/science/Jurassic-Period  Koch, C. Fred and Hansen,. Thor Arthur (2024, August 28). Cretaceous Period. Encyclopedia Britannica. https://www.britannica.com/science/Cretaceous-Period Jurassic Period. (n.d.). https://www.nationalgeographic.com/science/article/jurassic Triassic Period. (n.d.). https://www.nationalgeographic.com/science/article/triassic The Editors of Encyclopedia Britannica. (2024, July 30). Geologic time | Periods, Time Scale, & Facts. Encyclopedia Britannica. https://www.britannica.com/science/geologic-time. What is the geological time scale? (n.d.). The Australian Museum. https://australian.museum/learn/australia-over-time/evolving-landscape/the-geological-time- scale/#:~:text=The%20geological%20time%20scale%20is,distances%20both%20vertically%20and%20 horizontally Neogene Period | Natural History Museum. (n.d.). https://natmus.humboldt.edu/exhibits/life-through- time/visual-timeline/neogene-period Paleogene Period | Natural History Museum. (n.d.). https://natmus.humboldt.edu/exhibits/life-through- time/visual-timeline/paleogene-period Republic of the Philippines Technological University of the Philippines – Manila College of Engineering Department of Civil Engineering PCS2-M Professional Course- Specialized 2 Written Report Composition of Earth Submitted by: Cabading, Laryn Jake Dela Cruz, Bryan Jay Lessly, Lalaine Joyce G. Sumilang, Maryann M. Tapang, Joseph Cyril I. BSCE-4B Submitted to: Engr. Kevin M. Desales Date Submitted: September 23, 2024 SUBTOPICS Earth’s Layered Structure o Composition of the Crust o Composition of the Mantle o Composition of the Core Elemental Distribution in the Earth Mineralogy of Earth’s Layers Physical Properties of Earth’s Layers Seismic Wave Behavior and Composition I. INTRODUCTION The Composition and Structure of Earth The Earth, our home planet, is a dynamic and complex system composed of various layers and materials that interact to sustain life. Understanding the composition of the Earth is essential for grasping the geological processes that shape our environment, from the formation of mountains to the occurrence of earthquakes. The Earth is primarily made up of three main layers: the crust, mantle, and core, each with distinct characteristics and compositions. II. EARTH’S LAYERED STRUCTURE The Earth is structured in four main layers:  Crust: The outermost layer, varying in thickness.  Mantle: Lies beneath the crust, extending to the outer core.  Outer Core: A liquid layer composed primarily of iron and nickel.  Inner Core: A solid, dense layer composed of iron and nickel. COMPOSITION OF THE CRUST Earth's Crust “Crust” describes the outermost shell of a terrestrial planet. Earth's crust is generally divided into older, thicker continental crust and younger, denser oceanic crust. The dynamic geology of Earth's crust is informed by plate tectonics.. Earth's Layers  Earth comprises three main layers: the crust, mantle, and core. The crust sits atop the mantle, which contains semi-solid magma, while the core is a hot, dense metal center. Lithosphere  The crust and upper mantle form the lithosphere, a rigid geological unit. The depth varies, with the Moho being the boundary between the crust and mantle. Isostasy  Isostasy explains how the crust "floats" on the mantle, with balance depending on crust density, thickness, and mantle dynamics. Temperature Variability  Crust temperatures vary widely, from ambient surface conditions to around 200-400°C (392-752°F) near the Moho. Crust Formation  Earth's crust formed billions of years ago from molten materials, with heavier elements sinking to create the core. As the mantle cooled, the crust developed through processes like outgassing. Types of Rocks  The crust is composed of igneous (granite and basalt), metamorphic (slate and marble), and sedimentary rocks (sandstone and shale). Crust and Lithosphere The Earth's outermost layer, known as the crust, is a thin, brittle shell composed of rock. It varies in thickness and composition across two main types: 1. Oceanic Crust: o Thinner (3-6 miles), denser, primarily composed of basalt.  o Composed mainly of basalt and gabbro. o Formed from magma that erupts on the seafloor. o Covered by sediments, mainly mud and shells of tiny sea organisms. o Thicker near the shore due to sediment deposition from rivers and winds. o Denser than continental crust, causing it to sink into the mantle and form ocean basins. 2. Continental Crust: o Composed of diverse igneous, metamorphic, and sedimentary rocks. o Predominantly granite, which is less dense than oceanic crust. o Thicker and lighter, causing it to rise higher on the mantle, forming continents. o Thicker (20-30 miles), less dense, primarily composed of granite. Extraterrestrial Crust  Other terrestrial planets and moons have crusts formed from silicate minerals but are not shaped by tectonic plates. For example, the Moon's crust is thicker than Earth's, and Mars features the tallest mountains in the solar system. Lithosphere:  The lithosphere includes the crust and the uppermost part of the mantle.  It is about 100 km thick and behaves as a brittle, rigid solid.  When subjected to stress, the lithosphere breaks, leading to earthquakes. Frequently Asked Questions 5. Broken into plates that move due to How thick is Earth's crust? mantle convection driven by core  The continental crust is about 20 to heat. 30 miles thick, while the oceanic Where is Earth's crust the thinnest? crust ranges from 3 to 6 miles thick.  The thinnest crust is oceanic, at How old is Earth's crust? about 3 miles thick, compared to the  The oldest oceanic crust is around thinnest continental crust at around 200 million years old, while the 20 miles. oldest continental crust is about 3 to What is Earth's crust made of? 4 billion years old.  Composed of approximately 46.6% What are 5 facts about the crust? oxygen, 27.7% silicon, 8.1% 1. Thickness ranges from 5 to 50 aluminum, 5% iron, and other kilometers. elements. 2. Composed of lighter continental and How hot is the crust? denser oceanic crust.  Temperatures vary, typically 3. Dominant elements are oxygen and between 400 to 750°F (200 to silicon. 400°C), with some estimates 4. The deepest hole dug is about 12.2 reaching up to 1,000°F (600°C) kilometers.  COMPOSITION OF THE MANTLE River of Rock The next layer, the mantle, is often mistaken for lava, but it is actually composed of rock that flows under pressure, similar to road tar. This movement creates slow currents as hot rock rises from the depths while cooler rock sinks. The mantle is approximately 1,800 miles (2,900 kilometers) thick and is divided into two sections: the upper mantle and the lower mantle. Mantle The Earth's mantle is a solid layer of rock that lies beneath the crust and extends to the core. It is characterized by its extreme heat and solid state, playing a crucial role in the Earth’s geodynamics. 1. Composition: o Primarily composed of ultramafic rock peridotite, which is rich in iron and magnesium silicate minerals. 2. Heat Properties: o The mantle is extremely hot due to heat conducted from the core and radioactive decay within the Earth. o Heat transfer occurs through two main processes: Conduction & Convection 3. Convection Currents: o Convection occurs as the core heats the bottom layer of the mantle, decreasing its density and causing it to rise. o As the material reaches the surface, it cools, spreads horizontally, and eventually sinks back down once it becomes dense again. o This cyclical movement, known as a convection cell, drives plate tectonics and influences geological activities such as volcanic eruptions and earthquakes. Mantle Convection Cycle 1. Heating at the Core: Mantle material at the core heats up, particles move rapidly, and density decreases.  2. Rising Material: Heated material rises towards the crust. 3. Horizontal Spread: Upon reaching the crust, it spreads horizontally. 4. Cooling: The material cools down, becomes denser, and starts to sink. 5. Sinking: Cooler, denser material sinks back towards the core. 6. Cycle Repeats: The material is heated again, completing the convection cell. Convection Cells: Mantle convection operates similarly to boiling water in a pot, where heat from radioactive isotopes deep within the Earth warms certain areas, causing hot material to rise while cooler material sinks. This creates a circular motion known as convection currents. Where Convection Occurs: The convection cycle occurs in the mantle beneath the Earth's crust. The asthenosphere's plastic-like properties allow for the movement of materials, enabling the convection process that drives plate tectonics. Impact on Plate Tectonics: As mantle convection rises, it forms mid-ocean ridges through tension, while sinking material exerts compressional forces that break apart the lithosphere into major and minor tectonic plates. This dynamic is known as "slab pull." Relation to Continental Drift: Continents are carried along with the tectonic plates, akin to standing on a moving conveyor belt. This passive movement over millions of years is referred to as continental drift, illustrating how continents are displaced by the underlying mantle convection. The mantle is divided into two distinct layers: the upper mantle and the lower mantle. Upper Mantle The upper mantle extends from the base of the Earth's crust down to about 410 miles (660 kilometers). This region includes the lithospheric mantle and the asthenosphere.   Lithospheric Mantle: This rigid layer is combined with the Earth's crust to form tectonic plates.  Asthenosphere: Beneath the lithosphere, this semi-solid layer allows for the movement of tectonic plates. Lower Mantle The lower mantle extends from about 410 miles (660 kilometers) to the Earth's core, reaching depths of about 1,800 miles (2,900 kilometers)  Characteristics: This layer is denser and exhibits higher pressure than the upper mantle.  Temperature and Dynamics: Temperatures in the lower mantle can reach up to 4,000 degrees Celsius (7,232 degrees Fahrenheit). Frequently Asked Questions 3. What is the Earth's mantle made of? 1. What are 5 facts about the mantle? The mantle consists mostly of ultramafic  The mantle comprises 84% of rock, such as peridotite, which is high in Earth's volume. magnesium and lower in silicate compared  It extends from 35 to 2,980 to the felsic rocks found in the continental kilometers below the surface. crust.  Mostly solid rock, it behaves like a 4. How many parts does the mantle viscous fluid over geological time. have? The mantle is divided into the upper  Temperatures range from 200 to and lower mantle. The upper mantle 4,000 degrees Celsius. includes the lithospheric mantle,  Convection currents in the mantle asthenosphere, mesospheric mantle, and drive plate tectonics. transition zone, while the lower mantle 2. Is the mantle solid or liquid? The consists of the remaining mesospheric mantle is primarily solid rock but acts like a mantle. viscous fluid over long periods, forming 5. What is in the mantle of the Earth? convection currents that drive plate The mantle is the largest layer of Earth's tectonics. interior, making up about 84% of its volume. It is mostly composed of ultramafic rock and 6. How old is the mantle? The mantle forms convection currents due to heat from began to form about 10 million years after the core. Earth itself, which formed approximately 4.5 billion years ago. COMPOSITION OF THE CORE The next layer is the CORE, the central or innermost portion of the Earth, lying below the mantle and consisting of heavy metals. The Earth’s core lies beneath the crust and the mantle. It is divided into 2 layers, the liquid outer core, and a solid inner core The Earth’s core lies beneath the crust and the mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface and has a radius of about 3,485 kilometers (2,165 miles). CORE The mantle is divided into two distinct layers: the upper mantle and the lower mantle. Outer Core The outer core, about 2,200 kilometers (1,367 miles) thick, is mostly composed of liquid iron and nickel. The NiFe alloy of the outer core is very hot, between 4,500° and 5,500° Celsius (8,132° and 9,932° Fahrenheit). The liquid metal of the outer core has very low viscosity, meaning it is easily deformed and malleable. It is the site of violent convection. The churning metal of the outer core creates and sustains Earth’s magnetic field. The hottest part of the core is actually the Bullen discontinuity, where temperatures reach 6,000° Celsius (10,800° Fahrenheit)—as hot as the surface of the sun. Inner Core The inner core is a hot, dense ball of metals comprised of about 85% iron and 15% nickel and other metals. It has a radius of about 1,220 kilometers (758 miles). Temperature in the inner core is about 5,200° Celsius (9,392° Fahrenheit). The pressure is nearly 3.6 million atmospheres (atm). The temperature of the inner core is far above the melting point of iron. However, unlike the outer core, the inner core is not liquid or even molten. The inner core’s intense pressure— the entire rest of the planet and its atmosphere—prevents the iron from melting. The pressure and density are simply too great for the iron atoms to move into a liquid state. Because of this unusual set of circumstances, some geophysicists prefer to interpret the inner core not as a solid, but as a plasma behaving as a solid. The liquid outer core separates the inner core from the rest of Earth, and as a result, the inner core rotates a little differently than the rest of the planet. It rotates eastward, like the surface, but it’s a little faster, making an extra rotation about every 1,000 years. Magnetism Earth’s magnetic field is created by the motion of the molten metals in the outer core. Magnetism in the outer core is about 50 times stronger than it is on the surface. It might be easy to think that Earth’s magnetism is caused by the big ball of solid iron in the middle. But in the inner core, the temperature is so high the magnetism of iron is altered. Once this temperature, called the Curie point, is reached, the atoms of a substance can no longer align to a magnetic point. Earth’s Magnetic Field Earth’s magnetic field is crucial to life on our planet. It protects the planet from the charged particles of the solar wind. Without the shield of the magnetic field, the solar wind would strip Earth’s atmosphere of the ozone layer that protects life from harmful ultraviolet  radiation. Although Earth’s magnetic field is generally stable, it fluctuates constantly. As the liquid outer core moves, for instance, it can change the location of the magnetic North and South Poles. The magnetic North Pole moves up to 64 kilometers (40 miles) every year. Fluctuations in the core can cause Earth’s magnetic field to change even more dramatically. Geomagnetic pole reversals, for instance, happen about every 200,000 to 300,000 years. Geomagnetic pole reversals are just what they sound like: a change in the planet’s magnetic poles, so that the magnetic North and South Poles are reversed. These “pole flips” are not catastrophic, scientists have noted no real changes in plant or animal life, glacial activity, or volcanic eruptions during previous geomagnetic pole reversals. Frequently Asked Questions 1. What are 5 facts about the core?  Scientists believe that the Earth’s inner core is growing slowly, as the liquid outer core at the boundary with the inner core cools and solidifies due to the gradual cooling of the Earth's interior.  The Earth’s core is 2442 km in diameter, making it just 30% smaller than the moon.  Although the Earth’s core is mostly iron and nickel, it also includes other elements that are capable of dissolving in iron such as cobalt gold and platinum. These elements are called Siderophiles.  The inner core makes up approximately 1.7% of the Earth’s total mass, while the outer core makes up 30.8% of the Earth’s total mass.  The inner core travels 1/3 of a second faster than the surface of the Earth. 2. How did scientists know that the inner core is solid? In the 20th century, geoscientists discovered an increase in the velocity of p-waves, another type of body wave created by earthquake, at about 5,150 kilometers (3,200 miles) below the surface. The increase in velocity corresponded to a change from a liquid or molten medium to a solid. This proved the existence of a solid inner core. 3. How did scientists know that the outer core is liquid?  Earthquakes generate different kinds of seismic waves that behave differently when passing through different materials. Notable, one of the types of waves (S waves) don't pass through liquids. This creates a kind of "shadow" that tells us that the outer core is liquid. Elemental Distribution in the Earth The abundance of chemical elements in the universe is dominated by the large amounts of hydrogen and helium which were produced during the Big Bang. Remaining elements, making up only about 2% of the universe, were largely produced by supernovae. Elements with even atomic numbers are generally more common than their neighbors in the periodic table, due to favorable energetics of formation, known as the Oddo–Harkins rule. The Earth is formed from the same cloud of matter that formed the Sun, but the planets acquired different compositions during the formation and evolution of the Solar System. In turn, the natural history of the Earth caused parts of this planet to have differing concentrations of the elements. The mass of the Earth is approximately 5.97×1024 kg. In bulk, by mass, it is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminum (1.4%); with the remaining 1.2% consisting of trace amounts of other elements. EARTH'S ELEMENT COMPOSITION Iron (Fe) Oxygen (O) Silicon (Si) Magnesium (Mg) Sulfur (S) Nickel (Ni) Calcium (Ca) Aluminum (Al) Other Elements 1.8 1.5 1.4 1.2 2.9 13.9 32.1 15.1 30.1 The bulk composition of the Earth by elemental-mass is roughly similar to the gross composition of the solar system, with the major differences being that Earth is missing a great deal of the volatile elements hydrogen, helium, neon, and nitrogen, as well as carbon which has been lost as volatile hydrocarbons. Elemental Distribution in the Earth’s Crust The mass-abundance of the nine most abundant elements in the Earth's crust is roughly: oxygen 46%, silicon 28%, aluminum 8.3%, iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium 2.0%, and titanium 0.61%. Other elements occur at less than 0.39%. ELEMENTAL DISTRIBUTION IN THE EARTH’S CRUST Oxygen (O) Silicon (Si) Aluminum (Al) Iron (Fe) Calcium (Ca) Sodium (Na) Magnesium (Mg) Pottasium (K) Titanium (Ti) Others 2.4 0.61 0.15 2.5 4.2 2 5.6 8.3 46 28 Mineralogy of Earth’s Layers The mineralogy of Earth refers to the study and distribution of minerals that make up the planet's crust, mantle, and core. Minerals are naturally occurring, inorganic solids with a definite chemical composition and a crystalline structure. The most important minerals in Earth’s makeup are silicates, oxides, sulfides, and native elements. Here's a breakdown of the Earth’s mineralogy by layers: 1. Crust: This is the outermost layer of the Earth, consisting of solid rock. It's divided into two types: continental crust (thicker and less dense) and oceanic crust (thinner and denser). The most common minerals in the crust are silicates, which contain silicon and oxygen. Some common silicate minerals include quartz, feldspar, mica, and olivine.  Continental Crust: This is thicker and less dense than oceanic crust. It's primarily composed of granite, a rock made up of quartz, feldspar, and mica. Other common minerals found in the continental crust include biotite mica, hornblende, and garnet.  Oceanic Crust: This is thinner and denser than continental crust. It's primarily composed of basalt, a volcanic rock rich in plagioclase feldspar, pyroxene, and olivine. Other minerals found in oceanic crust include amphibole, magnetite, and ilmenite.  2. Mantle: This layer lies beneath the crust and makes up the majority of Earth's volume. It's composed primarily of silicate rocks, but the minerals are denser and more magnesium-rich than those in the crust. Peridotite is a common rock type in the upper mantle, containing minerals like olivine and pyroxene.  Upper Mantle: This layer is primarily composed of peridotite, a rock made up of olivine and pyroxene. Other minerals found in the upper mantle include garnet, spinel, and amphibole.  Transition Zone: This layer is characterized by a significant change in mineral structure, as olivine transforms into denser minerals like spinel and ringwoodite.  Lower Mantle: This layer is believed to be composed of silicate minerals, but the specific composition is still debated. Some proposed minerals include bridgmanite, ferropericlase, and magnesiowüstite. 3. Core: The Earth's core is divided into an outer core (liquid) and an inner core (solid). The outer core is primarily composed of iron and nickel, along with smaller amounts of other elements. The inner core is believed to be composed of solid iron and nickel.  Outer Core: This layer is liquid and is believed to be composed primarily of iron and nickel, along with smaller amounts of other elements like sulfur and oxygen.  Inner Core: This layer is solid and is believed to be composed primarily of iron and nickel. Physical Properties of Earth’s Layers Earth can be divided into five layers based on physical properties; such as whether the layer is solid or liquid. 1. Lithosphere (rigid) 2. Asthenosphere ( soft-plastic) 3. Mesosphere (stiff-plastic) 4. Outer Core (liquid) 5. Inner Core (solid)  1. Lithosphere (Sphere of Rock) Lithosphere is derived from the Greek word "lithos" meaning stone, refers to the solid and rigid outermost physical layer of the Earth. The lithosphere is consists of:  The crust, which can be divided into two subtypes: o Continental Crust: Thicker and less dense than oceanic crust, its thickness ranges from 40 kilometers to 280 kilometers. It forms the foundation of the Earth's continents and is responsible for much of the planet's geological diversity, especially in mountain ranges and other elevated terrains. o Oceanic Crust: Thinner but denser compared to continental crust. Its thickness varies from nearly zero to an average of 140 kilometers. Oceanic crust is generally associated with ocean basins. o The uppermost mantle, which is part of the solid Earth but contributes to the lithosphere's rigidity. The average thickness of the lithosphere is about 100 kilometers or 60 miles, though it can reach up to 250 kilometers equivalent to 155 miles or more beneath older, more stable parts of continents. This thickness or depth is influenced by age and tectonic activity, with older lithospheric regions generally being thicker. Lithosphere is divided into several large and small segments known as tectonic plates. These plates are not stationary but move slowly, the fastest plate races at 15 centimeters equivalent to 6 inche per year and the slowest plate crawls at only 2.5 cm per year. Earth has 7 major and 8 minor plates and the movement and interaction of these plates are responsible for significant geological phenomena such as earthquakes, volcanic activity, and the formation of mountains. 2. Asthenospheren (Weak Sphere) The asthenosphere is a semi-fluid or semi- plastic layer located beneath the Earth's lithosphere. It is derived from the Greek word "astheno-" meaning weak, the asthenosphere's defining characteristic is its ability to move. This layer, unlike the solid and rigid lithosphere above, is more ductile, allowing the lithospheric plates to glide over it. The asthenosphere is found at a depth of approximately 80 to 200 kilometers beneath the Earth's surface. It is composed of partially molten rock, which remains close to its melting point at temperatures around 1500°C. However, the high pressure at these depths prevents it from fully melting. Unlike the lithosphere, which is broken into tectonic plates, the asthenosphere is relatively continuous. One of the most crucial roles of the asthenosphere is to facilitate the movement of tectonic plates. The lithosphere, essentially "floats" on the asthenosphere, which behaves like a conveyor belt, transporting the plates slowly across the planet’s surface. This movement is driven by convection currents within the asthenosphere, where hotter material rises and cooler material sinks, creating a cycle that causes the lithospheric plates above to shift. The asthenosphere is unique to Earth, as no other planet in the solar system is known to possess this layer. The presence of water on Earth is thought to be a crucial factor in the formation of the asthenosphere, as it contributes to the partial melting of the mantle, giving the layer its fluid-like properties. 3. Mesosphere (Lower Mantle) The mesosphere, also referred to as the lower mantle, is a region of the Earth's interior located below the asthenosphere and above the Earth's core. Unlike the semi-fluid and ductile asthenosphere, the mesosphere is significantly more rigid and less mobile due to the extreme pressures and temperatures it experiences at great depths. The mesosphere plays a key role in the Earth's structural composition and the behavior of seismic waves. The mesosphere is located at a depth of approximately 650 to 2900 kilometers beneath the Earth’s surface. It is subjected to immense pressures and temperatures, far greater than those in the layers above. These extreme conditions cause minerals to transform into different structures or pseudomorphs, continuously changing their forms as they adjust to the pressure and temperature gradients. Between the upper mantle and the mesosphere lies a transition zone, which spans from approximately 410 to 660 kilometers below the surface. This zone is marked by distinct changes in seismic velocity due to the alteration of minerals into new forms under pressure. The transition zone acts as a boundary where seismic waves behave differently, often slowing down or being reflected. This zone sometimes acts as a physical barrier that limits the movement of materials between the upper and lower mantle. Once below the transition zone, the mesosphere becomes relatively uniform in its composition and structure until it approaches the Earth's core. Unlike the more dynamic layers above, the lower mantle exhibits consistent mechanical properties, making it more resistant to flow and deformation. 4. Outer Core The Earth's outer core is a fully liquid layer composed mostly of molten iron and nickel, with minor elements such as sulfur and oxygen. It is the only completely liquid layer within the Earth, with temperatures ranging from about 4,500°C to 6,000°C. It extends from a depth of approximately 2,890 kilometers to 5,150 kilometers, making it about 2,300 kilometers thick. The outer core is a crucial component of the Earth's structure, playing a significant role in generating the planet's magnetic field and maintaining environmental conditions that support life. The convective flow of this molten iron and nickel is responsible for generating the Earth’s magnetic field. The movement of electrically conductive materials within the outer core creates the dynamo effect, which produces the protective magnetic field that surrounds the Earth. The magnetic field generated by the outer core is essential for life on Earth. It protects the planet from harmful solar and cosmic radiation, helps retain the atmosphere, and prevents life-supporting gases like oxygen from being stripped away. Without this magnetic field, Earth would be exposed to solar winds, similar to what has happened on Mars, leading to a loss of water and a breathable atmosphere. 5. Inner Core The inner core is the innermost part of the Earth, located at a depth of about 5,150 kilometers, extending to the center of the Earth at 6,371 kilometers. It is a solid sphere primarily composed of iron and nickel, with an estimated thickness of 1,220 kilometers. In 1936, Danish geophysicist Inge Lehmann was the first to provide evidence of the outer core's liquid nature and the existence of a solid inner core within it. Lehmann's discovery was based on her analysis of seismic waves, which behave differently when passing through solid and liquid layers. The inner core consists mainly of iron, with traces of nickel and lighter elements such as sulfur and oxygen. Its density is extremely high, around 16 grams per cubic centimeter, making it as dense as an iron-nickel meteorite. Although the temperatures within the inner core exceed 5,000°C, the immense pressure prevents the iron and nickel from melting, keeping the inner core in a solid state. The inner core grows slowly over time as the molten outer core cools and solidifies at its boundary. As heat escapes from the Earth's interior and is transferred to the outer layers, the outer core gradually solidifies at the inner core's surface, causing the inner core to expand. Seismic Wave Behavior and Composition The shaking from an earthquake travel away from the rupture in the form of seismic waves. Seismic waves are measured to determine the location of the earthquake, and to estimate the amount of energy released by the earthquake (its magnitude). Seismic waves are vibrations or oscillations that travel through the Earth, often as a result of sudd