Earth and Life Science First Quarter Reviewer (PDF)

FIRST QUARTER (REVIEWER) 1ST SEMESTER – S.Y. 2023-2024 EARTH AND LIFE SCIENCE EARTH EARTH is the only planet in the solar system that can harb...

FIRST QUARTER (REVIEWER) 1ST SEMESTER – S.Y. 2023-2024 EARTH AND LIFE SCIENCE EARTH EARTH is the only planet in the solar system that can harbor life because of the following reasons: o It has liquid water; o It has surface or lithosphere which includes the crust and the upper mantle; and o It has atmosphere that shelters it from the worst of the sun’s rays. o Earth is habitable because it has the right distance from the sun ▪ If the Earth is too near to the sun, the glaciers (ice) will melt, resulting to the increase in sea levels, therefore the continents will be submerged in bodies of water. ▪ If the Earth is too far to the sun, there will be an extreme coldness in it that may freeze every living organism to death. Also, oceans would be covered in ice, causing them to release less carbon dioxide and vapor. o The Earth is kept warm by an insulating atmosphere o There are chemical ingredients for life including water and carbon EARTH SUBSYSTEMS Earth System is essentially a closed system. o A closed system is a system in which there is only an exchange of heat or energy and no exchange of matter. ▪ Examples: The Earth receives energy from the sun and return some of this energy to space. Movement of air with different temperature. The hot air goes up because it is less dense than the cold air and the cold air goes down because it is denser that the hot air. Also, the hot air moves faster since it is less dense than the cold air that’s why the heat is being transferred from hotter surface to the colder surface. Earth System Science is the study of how the four spheres of the Earth system interact continually, each affecting the others. o Examples of System Interactions: ▪ Volcanoes erupt, sending ash and gases into the air and sending lava and ash down onto surrounding forests and human habitations. ▪ Hurricanes sweep across the ocean and onto the land, damaging the dwellings of people who live along the coast. ▪ Earthquakes can damage buildings which may kill people, as well as cause fires which release gases into the air. Earthquakes in the ocean may cause a tsunami which can eventually hit land and kill both animals and people. ▪ Typhoons. A typhoon forms when winds blow into areas of the ocean where the water is warm. These winds collect moisture and rise, while colder air moves in below. This creates pressure, which causes the winds to move very quickly. The winds rotate, or spin, around a center called an eye. Eye is the center region where the wind speed is very less due to low pressure. Tail is the part which is far from the land area and is very devastating. MINERALS Minerals are the ingredients of rocks or rocks are made up of minerals. It makes up the rocks beneath your feet, the soil that supports plants, and the deep rock of Earth’s mantle. o naturally occurring (not man-made or machine generated), inorganic elements (not a by-product of living things) or compounds with specific physical and chemical properties. MINERAL PROPERTIES: o Color - least useful property in identifying minerals. o Streak - The color of a minerals’ powder. “streak test” o Hardness - The ability of a mineral to resist being scratched or to abrasion. ▪ “Scratch test” - If mineral A can scratch mineral B, what does that tell us about the relative hardness of each mineral? ▪ Advantages of Moh’s Hardness Scale Easy to do Can be done anywhere, anytime, as long as it is not dark Relevant to geologists to roughly identify minerals using scratch kits. ▪ Disadvantages of Moh’s Hardness Scale Qualitative, not quantitative Cannot be use to test the accurate hardness of industrial minerals o Luster - How the minerals surface reflects light. ▪ Metallic - generally opaque and exhibit a resplendent shine similar to a polished metal. Example: Pyrite (fool’s gold) ▪ Non- metallic - vitreous (glassy), adamantine (brilliant/diamond-like), resinous, silky, pearly, dull (earthy), greasy, among others. o Fracture/Cleavage – ▪ Fracture - Mineral breaks unevenly or irregularly  ▪ Cleavage - The tendency of a Mineral to break evenly along its weakest plane. o Crystal Form/Habit - The external shape of a crystal or groups of crystals is displayed / observed as these crystals grow in open spaces. o Specific Gravity - The ratio of the density of the mineral to the density of water (1 g/cm3) o Sectility - ability of minerals to be sliced by a knife. ▪ Example: Gypsum o Tenacity - describes the minerals reaction to stress. ▪ Brittleness- a mineral turns into powder. ▪ Malleability a mineral can be flattened by pounding with a hammer. ▪ Ductility- A mineral can be stretched into wire. ▪ Flexible but inelastic - Minerals are bent but they remain in the new position. ▪ Flexible and elastic - Minerals are bent, and they bring back to their original position. ROCKS A rock is a naturally occurring solid aggregate of one or more minerals. The aggregate minerals forming the rocks are held together by chemical bonds. TYPES OF ROCKS 1. Igneous Rocks Igneous rock begins as magma. formed from hardening and crystallization of magma or molten material that originates deep within the earth. CLASSIFICATION OF IGNEOUS ROCKS Intrusive Igneous Rocks: magma pushes into surrounding rock below the Earth’s surface. The intrusive igneous rocks have very large crystals (coarse grained) since the cooling process is slow. Extrusive Rocks: forms when magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formed. The crystals are very small (fine-grained) since the cooling process is fast. CLASSIFICATION IGNEOUS ROCKS BASED ON COMPOSITION: 1. Composition - it refers to rock’s mineral and chemical make-up. o Felsic – igneous rocks that are light in colors; feldspar and silicates o Mafic – dark-colored igneous rocks made up of magnesium, calcium and iron o Intermediate – refers to igneous rocks between mafic and felsic composition. o Ultramafic – denotes igneous rocks that composed chiefly of mafic minerals. Example: Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. The composition of the rock is mafic, fine grained, extrusive Why and how magma rises up? Magma is less dense than the surrounding country rock. Magma rises faster when the density contrast between the magma and the country rock is greater. At shallower levels (surface), magma starts to accumulate and slowly solidifies. When the magma solidifies at depth, it can form different types of plutonic bodies. Magmas with low viscosity flow more easily than those with high viscosity. Mafic magma is less viscous than silicic (felsic-light colored) magma because it is hotter and contains less silica. A felsic rock has high amount of silica. Therefore, the lighter the igneous rock, the higher the silica content. 2. Metamorphic Rocks forms from pre-existing rocks: either metamorphic, igneous, sedimentary or other metamorphic rocks that have been altered by agents of metamorphism.  Metamorphism - transformation of one rock type into another. METAMORPHIC SETTINGS: o Contact Metamorphism - heated by nearby magma. Increased temperature changes the composition of the rock, minerals are changed into new minerals o Regional Metamorphism – pressure builds up in rocks that is deep within the Earth. Large pieces of the Earth’s crust collide and the rock is deformed and chemically changed by heat and pressure. Produces the greatest volume of metamorphic rock. o Burial Metamorphism – occurs at the bottom of thick sedimentary piles. AGENTS OF METAMORPHISM o Heat. The most important agent. ▪ It has two sources CLASSIFICATION OF METAMORPHIC ROCKS BASED ON TEXTURE: Texture refers to the size arrangement and grains within the rock. Foliation - any planar arrangement of mineral grains or structural features within the rock. That is caused by high pressure. Specially for those rocks that are buried deeper. “The deeper you go in our Earth’s layers, the higher the pressure and temperature will be.” o Foliated - contain aligned grains of flat minerals.  Example: Gneiss o Non-Foliated – mineral grains are not arranged in plains or bands o Example: Marble More examples: 3. Sedimentary Rocks Sedimentary Rocks are formed at or near the Earth’s surface usually during erosion. No heat and pressure involved. Strata – layers of rock Stratification – the process in which sedimentary rocks are arranged in layers. Stratigraphy – branch of science that studies about how rock layers are formed. EXOGENIC PROCESSES Processes that happens on the Earth’s surface. It includes weathering, erosion, and deposition. WEATHERING Weathering refers to the process of disintegration and decomposition of rocks. There are two types of weathering: mechanical weathering and chemical weathering. MECHANICAL WEATHERING or PHYSICAL WEATHERING is the breakdown of rocks into pieces without any change in its composition. In this process, the size and shape of rocks changes and this occurs because of the following factors in the next slide. o FACTORS THAT AFFECTS MECHANICAL WEATHERING: o Pressure. Due to tectonic forces, granite may rise to form mountain range. After the granite ascends and cools, the overlying rocks and sediments may erode. o Temperature. Rocks expand and are fractured when expose to high temperature. However, if the temperature drops to 0°C (freezing point of water), it also expands and causes fracture. o Abrasion. The breakdown of rocks is caused by impact and friction. This primarily occurs during collision of rocks, sand, and silt due to current or waves along a stream or seashore causing sharp edges and corners to wear off and become rounded. o Organic Activity. The roots grow causing penetration into the crack, expand, and in the long run, break the rock. o Human Activities. Activities such as digging, quarrying, denuding forests and cultivating land contribute to physical weathering. o Burrowing Animals. Animals like rats, rabbits and squirrels excavate into the ground to create a space for habitation. CHEMICAL WEATHERING is the erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes.  o CHEMICAL REACTIONS AFFECTING CHEMICAL WEATHERING o Dissolution. It occurs in specific minerals which are dissolved in water. ▪ Examples of these minerals are Halite (NaCl) and Calcite (CaCO3). The formation of stalactites and stalagmites in caves are brought about by this chemical reaction. o Hydrolysis. Rock-forming minerals like amphibole, pyroxene, and feldspar react with water and form different kinds of clay minerals. o Oxidation. It is the response of oxygen with minerals. If the iron oxidizes, the mineral in rocks decomposes. Rusting is an example of this chemical reaction. Soil is a mixture of grains, organic matter, H2O, and gas. Erosion is the separation and removal of weathered rocks due to different agents like water, wind, and glacier that causes transportation of the material to where they are deposited. Plants, animals, and humans play an important role in the erosional process. The movement of sediments downslope under the influence of gravity is called mass wasting. Deposition is the process in which the weathered materials carried out by erosion settle down in a particular location. MAGMA FORMATION (MAGMATISM) Magmas are formed under certain circumstances in special locations deep in the crust or in the upper mantle. They are formed when conditions are right to cause preexisting solid rocks to melt. o SPECIAL CONDITIONS REQUIRED FOR THE FORMATION OF MAGMA o Decompression Melting. The decrease in pressure affecting a hot mantle rock at a constant temperature permits melting forming magma. This process of hot mantle rock rising to shallower depths in the Earth occurs in mantle plumes, beneath rifts and beneath mid-ocean ridges. o Flux Melting. Melting as a result of the addition of volatiles (water or carbon dioxide)—compounds that have low boiling points. When volatiles mix with hot, dry rock, the volatile decreases the rock’s melting point and they help break the chemical bonds in the rock to allow melting. o Heat-induced/heat transfer - Melting resulting from heat transfer from rising magma (heat transfer melting): A rising magma from the mantle brings heat with it and transfer heat to their surrounding cooler rocks at shallower depths which may melt. o What happens to the molten rocks when they reach the Earth’s surface? ▪ Since the surface has lower temperature compared to the inner surface of the Earth, the molten rocks will eventually cool down and crystalize. MOVEMENT OF PLATES AND FORMATION OF FOLDS AND FAULTS Folds are the bend notice in rocks. Faults are the plane dislocation where the rocks on one side of the fault had moved relative to rocks on the other side. It is a fracture that damages or breaks the rock layers. Once these moves or if there will be a vibration ithin these faults caused by different stresses, an earthquake may occur. o It can form in anyone of the three types of forces or stress: ▪ Compression. Rocks are pressed together to itself. ▪ Tension. Forces pulling in opposite directions, which results in strain that stretches and thins rocks. ▪ Shear. Slippage among planes parallel to imposed stress. Usually, the movement of plate under the Earth’s surface happened on the focus or the hypocenter. Meanwhile, epicenter is the point on the earth's surface directly above the focus of an earthquake or underground nuclear explosion. STRATIFICATION The figure on the right is a diagram of stratified sedimentary rocks. And based on the Law of Superposition, the older layer is under the younger. Meaning, Layer A comes first on the area than Layers, B-G. Geologists studies the rock layer while paleontologists are the one who studies the fossils that can be found in each layers of rocks. o Fossils. Remnants, impression, trace of an animal or plant of past geologic age that has been preserved in Earth’s crust. o Through that, paleontologists use different method like relative and absolute dating. o Relative dating tells how old something is in relation to other objects, but cannot provide a year or specific date of use. ▪ For example: The trilobite and ammonite are older than the dinosaurs and birds. Since they had compared the location in which layer do these fossils are present. o Absolute dating provides a specific calendar year for the occupation of a site. ▪ For example: The trilobites existed 480 million to 360 million years ago. Based on the diagram, Layer C and E have no fossils because these layers of rocks are result of cooling of lava. GEOLOGIC TIME SCALE EON- largest division of the geologic time scale; spans hundreds to thousands of million of years ago (mya) ERA- division in an Era that span time periods of tens to hundreds of millions of years PERIOD- a division of geologic history that spans no more than one hundred million years EPOCH- the smallest division of the geologic time scale characterized by distinctive organisms o Cambrian Period. Trilobites and other early arthropods appear o Devonian Period. The first seed plants had evolved. o Triassic Period. Reptiles increased in diversity and number, and the first dinosaurs appeared during this period along with the appearance of first mammals. o Jurassic Period. Many new dinosaurs emerged—in great numbers. Trivia: Eons and eras mostly end in “zoic” because there was animal life during those times.