Week 11 Geologic Timescale PDF

CHAPTER 7 (WEEK 11) GEOLOGIC TIME SCALE Geologic Time Scale Geologists have created the geologic time scale which is a scale that divides Earth’s 4.6 billion year history into distinct intervals of time.  The Geologic time scale is one of those amazing human endeavors to turn a...

CHAPTER 7 (WEEK 11) GEOLOGIC TIME SCALE Geologic Time Scale Geologists have created the geologic time scale which is a scale that divides Earth’s 4.6 billion year history into distinct intervals of time.  The Geologic time scale is one of those amazing human endeavors to turn a vast amount of evidence from astronomy, rocks, fossils, history, and politics into a nifty little diagram which makes the whole thing appear nice, neat, and resolved. The largest divisions of geologic time are EONS. The four eons in turn are divided into ERAS, which are the second-largest divisions of geologic time. Eras are divided PERIODS, which are the third-largest division of geologic time. Some periods are divided into EPOCH which is the fourth largest division of geologic time. The boundaries between the geologic time intervals represent major changes in Earth.  PRECAMBRIAN The Precambrian is the name given for the first super eon of Earth’s history. This division of time — about seven-eighths of Earth's history — lasted from the first formation of the planet (about 4.6 billion years ago) to the geologically sudden diversification of multicellular life known as the Cambrian Explosion (usually dated at about 542 million years ago). The Precambrian is usually considered to have three eons: the Hadean, the Archean, and the Proterozoic THE DIFFERENT EONS ARCHEAN EON 01(3.8– 2.5BILLION YEARS AGO 02 BILLION YEARS HADEAN EON (4.6 BILLION YEARS AGO – 3.8 BILLION YEARS AGO) AGO) The earliest known rocks The only rock that scientist have on Earth formed during this found from this eon are eon meteorite and ducks from the 03PHANEROZOIC EON 04 PROTEROZOIC EON moon. (2.5 BILLION YEARS AGO – 540 (540 MILLION YEARS AGO MILLION YEARS AGO) – PRESENT) The rock and fossil record mainly The first organisms with represents the Phanerozoic Eon, well-developed cells appeared which is the eon in which we live. this eon.  PALEOZOIC ERA Paleozoic means “old life”. The Paleozoic era lasted from about 540 to 248 million years ago. It is the first era that is well represented by fossils. The Paleozoic Era started 542 million years ago with the emergence of complex life forms and ended 251 million years ago with the largest mass extinction the world has ever experienced. It is the oldest and longest era of the Phanerozoic Eon. The era is usually broken down even further to six main periods: SIX MAIN PERIOD OF PALEOZOIC ERA CAMBRIAN ORDOVICIAN SILURIAN 542 to 488.3 488.3 to 443.7 443.7 to 416 million years ago million years ago million years ago DEVONIAN CARBONIFEROUS PERMIAN 416 to 359.2 299 to 251 million years ago 359.2 to 299 million years ago million years ago CAMBRIAN PERIOD First abundant record of marine life; trilobites dominant The Cambrian Period is the first geological period of the Paleozoic Era (the “time of ancient life”). This period lasted about 53 million years and marked a dramatic burst of evolutionary changes in life on Earth, known as the "Cambrian Explosion." TRILOBITES NAUTILOID FORAMS  ORDOVICIAN PERIOD The Ordovician Period was also characterized by the intense diversification (an increase in the number of species) of marine animal life in what became known as the Ordovician radiation. This event precipitated the appearance of almost every modern phylum (a group of organisms having the same body plan) of marine invertebrate by the end of the period, as well as the rise of fish. ECHINOIDS BLASTOIDS EURYPTERID  SILURIAN PERIOD During the Silurian, continental elevations were generally much lower than in the present day, and the global sea level was much higher. Large expanses of several continents became flooded with shallow seas, and mound-type coral reefs were very common. Fishes were widespread. Vascular plants began to colonize coastal lowlands during the Silurian Period, whereas continental interiors remained essentially barren of life. COOKSONIA SCORPION BONY FISH The Devonian, part of the Paleozoic era, is otherwise known as the Age of Fishes, as it spawned a remarkable variety of fish. The most formidable of them were the armored placoderms, a group that first appeared during the Silurian with powerful jaws lined with bladelike plates that acted as teeth. First amphibians, fishes are abundant. By the start of the Devonian, early terrestrial vegetation had begun to spread. These plants did not have roots or leaves like most plants today, and many had no vascular tissue at all. They probably spread vegetative, rather than by spores or seeds, and did not grow much more DIPTERUS FISH DORYASPIS CLADOSELACHE  CARBONIFEROUS PERIOD PENNSYLVANIAN MISSISSIPPIAN The Pennsylvanian Period, often The Age of Amphibians called the Coal Age, was a time Giant Salamanders Proliferate as of alternating land and sea. Vast Forests Spread When the sea was out, the low (Also called the LOWER coastal plains were covered with CARBONIFEROUS PERIOD) luxuriant forests of seed ferns, The Mississippian Period began ferns, scale trees, calamite trees, about 359 million years ago and and cordate trees. ended about 318 million years Eryops AMMONOIDS  PERMIAN PERIOD The Permian period lasted from 299 to 251 million years ago and was the last period of the Paleozoic Era. It affected many groups of organisms in many different environments, but it affected marine communities the most by far, causing the extinction of most of the marine invertebrates of the time MESOZOIC ERA Mesozoic means “middle life”. The Mesozoic era lasted from about 248 million years ago until about 35 million years ago. This era is also known as the Age of Reptiles. Dinosaurs inhabited the land and water. By the end of the Mesozoic era, about 50 percent of all species on Earth including the CAMBRIAN PERIOD The Mesozoic Era It is also called the Age of Reptiles and the Age of Conifers. The era is subdivided into three major periods: the Triassic, Jurassic, and Cretaceous, which are further subdivided into several epochs and stages. The Mesozoic was a time of significant tectonic, climate, and evolutionary activity. The era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would move into their current positions during the next era. TRIASSIC PERIOD The Triassic Period was the first period of the Mesozoic Era and occurred between 251 million and 199 million years ago. It followed the great mass extinction at the end of the Permian Period and was a time when life outside of the oceans began to diversify. herrerasaurus First dinosaur. Abundant cycads and conifers.  JURASSIC PERIOD At the beginning of the Jurassic, the Earth's continents were still jammed together, forming the supercontinent Pangaea, but they were beginning to drift apart. There had been a minor extinction at the end of the Triassic period, which gave rise to an abundance of dinosaurs in the Jurassic..  JURASSIC PERIOD First birds, first mammals. Dinosaurs and ammonites are abundant. Bird-like dinosaurs also flourished. (ARCHAEPTERY) Early mammals were developing and diversifying in the Jurassic. DAKOSAURUS MAMENCHISAURUS  CRETACEOUS PERIOD The Cretaceous period was the heyday of the dinosaurs. The Cretaceous period ended 65 million years ago with the extinction of the dinosaurs and many, many other prehistoric life forms. This mass extinction was the second-most extensive in the history of the Earth. Creta is the Latin word for chalk. The Cretaceous period is named for chalky rock from southeastern England that was the first Cretaceous period sediment studied. TYRANNOSAURUS REX PTERODACTYL  CENOZOIC ERA Cenozoic means “new life”. The Cenozoic era began about 65 million years ago and continues to the present. It is called the AGE OF MAMMALS. It was the interval of time during which the continents assumed their modern configuration and geographic positions and during which Earth’s flora and fauna evolved toward those of the present. The term Cenozoic, originally spelled Kainozoic, was introduced by English geologist John Phillips. TERTIARY PERIOD EOCENE EPOCH OLIGOCENE EPOCH PALEOCENE EPOCH The Eocene spans the time The Oligocene is often It started with the mass from the end of the considered an important time extinction event at the end of the Palaeocene Epoch to the of transition, a link between Cretaceous, known as the beginning of the Oligocene the archaic world of the Cretaceous-Paleogene (K-Pg) Epoch. The start of the tropical Eocene and the more boundary. This was a time Eocene is marked by a brief modern ecosystems of the marked by the demise of period in which the Miocene. Major changes non-avian dinosaurs, giant concentration of the carbon during the Oligocene included marine reptiles, and much other isotope 13C in the a global expansion of fauna and flora. The die-off of atmosphere was grasslands and a regression of the dinosaurs left unfilled exceptionally low in tropical broadleaf forests to ecological niches worldwide. comparison with the more the equatorial belt. common isotope 12C. TERTIARY PERIOD MIOCENE EPOCH PLIOCENE EPOCH The apes arose and diversified during the During the Pliocene, the tectonic Miocene epoch, becoming widespread in plates of India and Asia also collided, the Old World. In fact, by the end of this which formed the Himalayas. epoch, the ancestors of humans had split away from the ancestors of the During the Pliocene, the tectonic chimpanzees to follow their evolutionary plates of India and Asia also collided, path. which formed the Himalayas. In the Miocene seas, kelp forests made their first appearance and soon became one of Earth’s most productive ecosystems. The plants and animals of the Miocene were fairly modern. PALEOCENE EPOCH EOCENE EPOCH OLIGOCENE EPOCH MIOCENE EPOCH PLIOCENE EPOCH The Quaternary The Period Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers the time of glaciations classified as the Pleistocene and includes the present interglacial period, the Holocene. Part of the Cenozoic Era, the period is usually divided into two epochs — the Pleistocene Epoch, which lasted from approximately 2 million years ago to about 12,000 years ago, and the Holocene Epoch, which began about 12,000 years ago. The Quaternary Period has involved dramatic climate changes, which affected food resources and brought about the extinction of many species. The period also saw the rise of a new PLEISTOCENE EPOCH HOLOCENE EPOCH THANKS FOR LISTENING ! CREDITS: This presentation template was created by Slidesgo, including icons by Flaticon and infographics & images by Freepik Please keep this slide for attribution