Geology 101 Test #1 Study Guide
Geology 101 Test #1 Study Guide GEO 101
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This 11 page Study Guide was uploaded by Kayla Corbett on Tuesday February 16, 2016. The Study Guide belongs to GEO 101 at University of Alabama - Tuscaloosa taught by Dr. Natasha T. Dimova in Fall 2016. Since its upload, it has received 206 views. For similar materials see The Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 02/16/16
Study Guide for GEO 101002 Chapter 1 Q: Which are the two approaches applied in science in our efforts to understand natural world? Science is done through 1.) Observation of natural phenomena 2.) Performing experiments that try to simulate natural processes under controlled conditions Q: What is Earth Science (Geology)? The study of the Earth, focusing on its composition, behavior, and history Also, including atmosphere, hydrosphere, mantle, core, etc. Q: What do specialists in Mineralogy do? (similar question can be asked for any of the Geology disciplines, e.g. Geochronology, Oceanography etc.) Specialists in mineralogy study structure and properties of minerals. Q: Name three Geologic Theories that are considered the cornerstones of the study of Geology? 1. Plate Tectonics Theory 2. The Rock Cycle 3. Hydrological Cycle Chapter 10 Q: Name the three types of rocks in nature? 1. igneous 2. metamorphic 3. sedimentary Q: Which are the two methods applied in Geology (Geochronology) used to determine age of geological features? Relative Time age of features described in relation to one another Absolute Time number of years 1 Q: If you have a vertical sequence of rocks like on the picture below, which would be the oldest and which would be the youngest rock? (this is an example of a diagramtype question. Check also your lecture notes on diagrams and principles we used) In an undeformed sequence of rocks, oldest rocks are on the bottom and the youngest are on top. Q: Which geochronological principle stays that if you have a fragment within a rock, the fragment/inclusion must be older than the surrounding rock? Principle of Inclusions Q: What do Paleontologists study? The study of fossils Q: What is unconformity? A break in the rock record resulting from erosion and/or nondeposition of rock: sediment does not accumulate Q: What are the three steps in creating Angular Unconformity (I can ask for any of the three unconformities we studied). 1. layers undergo folding 2. erosion produces a flat surface 3. sea level rises and new layers of sediment accumulate Q: Which method do we use to determine the exact age of a rock? Isotopic dating Q: How do you understand the phenomenon radioactivity? Some elements that are in the composition of rocks are unstable and breakdown • Radioactivity occurs through different types of decay: alpha, beta, and gamma decay Q: If you have 20 atoms of a radioactive element (parent atoms) and the halflife of this element is 4 days. How many atoms you will have of the parent after 8 days? Five 2 Q: How old is the Earth? 4.6 billion years’ old Uranium Dating Chapter 11 Q: How does the “Big Bang” theory explain the formation of the Earth? 1. All matter/energy (the Universe) was packed into one point violently exploded 2. Led to creation of elements Q: Tell me at least one piece of evidence that supports the “Big Bang” theory. Galaxies appear to be moving away from each other at speeds proportional to their distance ("Hubble's Law“) 1. We are still “cooling down” 2. The availability of "light elements" Hydrogen (H) and Helium (He) found in the observable universethis is the original material for planet formation Q: The Hadean Eon is called “The Birth of the Earth” This is the time when Earth looked like a fireball, i.e. it was partially melted. During this time the main Earth’s compositional layers separated due to differences in their densities. Which are these four layers? 1. Inner core; 2. outer core; 3. mantle; and 4. crust (neglect atmosphere from picture) Q: How do we know about these four layers? From monitoring earthquakes: earthquake waves travel through different layers with different velocities Q: The Archean Eon is called “The Birth of Continents and first life” What did lead to formation of land/continents on Earth? Intensive volcanic activity Q: We have evidence that Oxygen (O ) s2arted accumulating in the atmosphere during the Achaean. How do we get this oxygen? Through the first photosynthesizing organisms that appeared during this period 3 Q: Which is the major event in terms of continental building during Proterozoic? Collision of smallpieces land into one single continent called Rodinia. Q: Geologists claim that the Precambrian (Haden, Archean, Protorezoic) covers about 90% of the Earth’s history. Can you tell me what do we have in terms of life, paleogeography, and atmosphere at the end of the Precambrian? In terms of: 1.) Life: we have simple life, single and some multicellular organisms 2.) Paleogeography: we have supercontinent Rodinia 3.) Atmosphere: we have oxygen and water vapor. Q: In terms of mountain building, can you tell me which is the mountain range that started building up during early Paleozoic? Taconic Orogeny, the Appalachian started developing during early Paleozoic. Q: Which is the most important event (in terms of life) that marks the Paleozoic Era? The most important event is the vast diversification of life, life just "exploded" during Paleozoic. It happened at the beginning of Paleozoic. Q: Which are the two most important paleogeography events that mark the end Paleozoic Era? 1.) the formation of supercontinent Pangaea 2) the final development of the Appalachians Q: When did the largest mass extinction in the Earth’s history happen? It happened at the very end of the Paleozoic: (96% of marine species and 70% of terrestrial species died) Chapter 3 Q: Give me at least two reasons why study minerals. Minerals are used as: 1.) Energy resources 2.) Raw materials for manufacturing chemicals for industrial use. 4 Q: Know the full definition for mineralthe building blocks of rocks 1.) naturally occurring solid 2.) has defined inorganic composition 3.) has crystalline structure KNOW VERY WELL THE RELATIONSHIP BETWEEN THE TERMS: ROCKMINERAL ATOMS Q: What do we mean by crystalline structure? Array of atoms organized in a specific way (pattern) in a mineral Q: What are atoms? Atoms are the basic unit of a chemical element. Q: What is an ion/anion? Ion: an atom that has extra positive charge because had lost electron Anion: an atom or a group of atoms with extra negative charge as they have accepted extra electrons. Q: What is an isotope? Atoms of the same chemical element with different number of neutrons of their nucleus. We used them for isotopic dating Q: Which are the ions building the mineral halite, i.e. the table salt (will be asked for some common minerals such as gypsum, quartz calcite etc.)? Sodium (Na+) and chloride (Cl) Q: What is the most specific thing about covalent bond/bonding? (Same question can be asked for metal, ion and van der Waals bondsbe familiar with them) The electrons in the bond are equally shared by the bonding atom. Q: Give me an explanation why diamond and graphite have such different physical properties although they are built of the same chemical element (i.e. carbon)? 5 The difference is due to their different mineral structure and bonds between the carbon atoms. The carbon atoms in the diamond mineral structure have strong bounds which makes diamonds so hard to break. In contrast, the graphite is built of different sheets/planes that are connected with week bonds. This is the reason graphite is so easy to slice in layers. Diamonds and graphite are called polymorphs Q: How do we identify minerals? By observation and by performing simple tests; we use a list of properties, Know the basic Primary Diagnostic Properties, number 18 in the lecture Q: Which are the most abundant elements on the Earth? Oxygen and Silicon Q: Which is the most abundant mineral group on the Earth and why? Silicates, because silicon and oxygen are the most abundant elements on the Earth Q: Name one Mafic silicate mineral? Olivine Q: Name one Felsic silicate mineral? Quartz or Feldspar, or Muscovite Q: Compare mafic versus felsic minerals in terms of structure, color, density properties, composition (inclusions). We did this in a table in class, use your class notes. Mafic:Simpler SiO2 structureDark colored; more denseContain iron and magnesium Felsic:More complex SiO2 structureLight colored; less denseNo iron or magnesium Chapter 4 Q: How do igneous rocks form and where with respect to the earth surface? 6 Igneous rocks are formed by the cooling and hardening of molten material called magma. Q: What is magma made of? Liquid portion (melt), solids, and volatiles. Q: What are the factors affecting magma composition? 1.) heat 2.) pressure 3.) volatiles Q: What is viscosity? Compare felsic versus mafic magmas in terms of viscosity. – Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma, and temperature. • Higher SiO 2silica) content magmas have higher viscosity than lower SiO con2ent magmas (viscosity increases with increasing SiO 2oncentration in the magma). • Lower temperature magmas have higher viscosity than higher temperature magmas (viscosity decreases with increasing temperature of the magma). Q: What is geothermal gradient?! The temperature increase with depth in the upper crust Q: What is the effect of pressure on the rock’s melting temperature? Decreasing the pressure (pressure drop) results in decompression of dissolved gasses and melting occurs at lower temperature. Q: How volatiles affect the melting point of rocks? They cause rocks to melt at lower temperature. Q: What is texture? Refers to the size and arrangement of crystals in the solid rock. Q: How the regime of cooling (i.e. how fast) affects the texture of a rock? Fast cooling results in small size minerals, slow cooling results in large minerals. 7 Q: What kind of texture an intrusive rock has? (same question can be asked about extrusive rock) A: Large size because the cooling is slow and isolated (GRADUALLY COOLING) in the subsurface. Q: What does the Bowen’s Reaction Series show? The sequence of crystallization of minerals in cooling magma Q: Which minerals crystallize first (i.e. at higher temperature) according to the Bowen’s Reaction Series? Name one of them. Ultramafic and Mafic minerals; Olivine+Pyroxene Q: Which minerals crystallize last (i.e. at lower temperature) according to the Bowen’s Reaction Series? Name one of them. Felsic minerals; Quartz+Muscovite Q: Aphanitic (finegrained) texture is formed via rapid rate of cooling. What kind of crystals (in terms of size) you would expect to have in such rock? An Igneous rock is the product of cooled solidified magma/lava. As magma/lava cools it goes through the process of crystallization which turns it into an igneous rock. The amount of time it takes for an igneous rock to form depends on its location and its composition. Chapter 6 Q: Define sedimentary rocks Rocks that were formed near or at the surface of the Earth by cementing together loose grains that have been produced by physical or/and chemical weathering; precipitation of minerals from water; growth of masses of shellproducing organisms. Q: What is physical weathering? (same question can be asked for chemical weathering) The physical/mechanical breakdown of rocks on Earth's surface. Q: Know about the main types of physical weathering? Frost wedging; unloading, thermal expansion, biological activity Q: What are the three pathways of chemical weathering? 8 Dissolution; oxidation; hydrolysis Q: What are the three factors affecting the rates of weathering? Surface area of the rock; rock composition; climate Q: What does happen with rocks that have been weathered? When they stay at the surface they evolve into soil; when they get buried they change into sedimentary rock. Q: What is the most important organic substrate in soil that supports life? Humus. Q: What are the main 5 steps in forming sedimentary rocks? (diagram) Weathering, erosion, transportation, deposition, lithification Q: What is the difference between erosion and weathering? Weathering is the breakdown and alteration of the rock (in place), while erosion is the removal of this material (i.e. clearing) from this place Q: What is lithification? The compaction of deposited material through cementation, diagenesis and extraction of water Q: There are four groups of sedimentary rocks: clastic, biochemical, organic, and chemical. Know about them, their origin and the physical properties. 1)clastic the residues of weathering 2)chemical/biochemical precipitates products of crystallization of ions that were dissolved during weathering. Q: Define the geological term bed. 9 A single layer of sediment or sedimentary rock with recognizable top and bottom Q: Define the geological term bedding plane. The boundary between two beds Q: Define the geological term strata. Several beds together Q: Define the geological term stratification (bedding). The overall arrangement of sediment into a sequence of beds. Q: What does a geologic map usually show? The distribution of formations presented in specific color code. Chapter 7 Metamorphism: a process of change Q: What is metamorphism? The transition of one rock (igneous, sedimentary and metamorphic) into another metamorphic rock by applying: 1.) high temperature and/or 2.) pressure; 3.) high temperature fluid Q: There are three main agents of metamorphism. Name them. 1.) high temperature 2.) pressure 3.) high temperature fluid Q: Which is the dominant agent of metamorphism? High temperature/heat Q: What is the source of heat (high temperature) in the subsurface that act as a metamorphic agent to rocks? Nearby magma body (magma chamber) or just result of geothermal gradient Q: Compare lithospheric pressure to differential pressurewhich one produces foliation in rocks? What is the result of lithospheric pressure? (diagram) 10 1. lithospheric pressure is pressure that is applied equally in all directions and it increases with depthgrains become closer to each other; shape does not change but the material shrinks and thus becomes denser 2. differential pressureapplied pressure is not equal to all sides; rock changes shape (distorted); minerals align (rock experience foliation) Q: What is the result of metamorphism? 1.) Recrystallizationminerals rearrange (foliation) 2.) New crystals growchemical reactions occur due to heating the material 3.) Metasomatismrock composition change because hot circulating water through the rock dissolves partially the rock and other minerals precipitate when water cools down. Q: Describe the metamorphic changes in a rock with increase of temperature and pressure. Use the example: shale>slate>phylite> shist>gneiss We observe changes in both mineral size and mineral orientation (foliation) and even composition (gneiss) 1. mica starts growing in mica flakes that gives slaty cleavage 2. mica crystals continue growing and become more defined oriented (more definedfoliation) 3. large mica crystalsrock has shiny appearance 4. minerals are not only aligned (oriented) but atoms migrate into forming bands ofdark and light material Q: What do we mean when we say a rock has slaty cleavage? Means we can split the rock into planar surfaces (sheets) Q: If you have Slate (a low grade metamorphic clayrich mineral) and you put it under pressure and high temperature, what would be the highest grade metamorphic mineral you can get? Gneiss Q: If you have limestone and put it under pressure and temperature, what would be the product of this metamorphism? Marble 11
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