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149 Cards in this Set
- Front
- Back
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What is Geology?
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Geology is the scientific study of Earth. Geology includes the study of Earth materials (rocks, soil), the inner workings of the planet, and the origin and changes of surface features.
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Geology includes what?
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Geology includes narrowly focused disciplines, many of which integrate knowledge from other sciences. Each discipline addresses specific aspects of the planet.
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Geologists strive to understand what?
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Geologists not only strive to understand the cause and distribution of geologic processes on and within Earth today, but also to describe the 4.5 billion year history of these processes on the planet.
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Why study Geology? Name all the spheres of the Earth
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4. Why study Geology? Name all the spheres of the Earth
Geologic studies are at the center of interdisciplinary efforts to understand the Earth system, which is compromised of the geosphere, hydrosphere, atmosphere, and biosphere. Geologic knowledge is required to locate and develop essential natural resources to avoid or diminish the effects of hazardous natural phenomena. |
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What is the scientific method?
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The scientific method seeks to understand natural phenomena by integrating the actions of asking questions, proposing explanatory hypothesis, and testing hypothesis.
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True or False? Why? Geologists use laboratory experiments less often to test hypothesis than do other scientists.
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True. The variables governing Earth processes usually are too many and the rates of the processes typically are too slow for direct experimental analysis.
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What are principles or laws?
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Generalizations about how nature is observed to work, whereas theories offer well-tested and accepted explanations of why natural systems work this way.
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What must hypothesis and theories be?
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To be scientific, hypotheses and theories must be testable by observing and measuring natural phenomena. Science remains an exciting and active human pursuit because all of nature is not explained by existing theory.
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What is the principle of uniformitarianism?
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The principle of uniformitarianism states that examined cases of both a process and its result can guide interpretation of visible results where the process was not witnessed. We can interpret ancient geologic features by understanding active processes observable today in nature or in the lab.
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What is the theory of plate tectonics?
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The plate tectonics theory states that the outer shell of Earth, the lithosphere, is divided into plates that move toward, away from, or past one another.
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How does the concept of work apply to the Earth?
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Movement of mass within Earth, on Earth’s surface, and in the atmosphere is evidence of work. Work requires energy. Geologically important energy sources are heat from the Sun and the internal heat of Earth, which results from natural radioactivity.
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What is evidence of the theory of plate tectonics?
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The interaction of plates at their boundaries accounts for the distribution of earthquakes, volcanoes, and actively growing mountain belts and provides a basis for interpreting most geologic processes and products.
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How is heat energy transferred?
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Heat energy is transferred from place to place by radiation, conduction, and convection. Convection involves simultaneous movement of mass and heat, and powers geologically important motion in the gaseous atmosphere and in the solid and liquid parts of Earth’s interior.
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What is potential energy?
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Potential energy is an important form of stored energy that objects possess because of their elevation. Conversion of potential energy to motion energy occurs when materials move from high elevation to low elevation.
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What are minerals?
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Minerals are chemical compounds consisting of combinations of atoms of one or more elements. Each mineral has a definitive, but possibly slightly varying, chemical composition.
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How do elements combine to make minerals?
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Minerals consist of combination of atoms held together by ionic, covalent, and less common metallic bonds, as well as the weak van der Waals forces. Ionic bonds are weaker than covalent bonds, in which atoms share electrons. Many minerals exhibit combinations of ionic and covalent bonds.
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How is the water molecule structured?
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The neutral, but lopsided, water molecule has a weak positive charge at one end and a slight negative charge at the other. These charges pull apart some weakly bonded ion, causing some minerals to dissolve in water.
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What are organic compounds?
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Continaing mostly carbon and hydrogen atoms. CANNOT BE MINERALS!
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What is the definition of a mineral?
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A mineral is a naturally occurring inorganic solid with a definite, only slightly variable chemical composition and an ordered atomic structure.
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True or False? The physical properties of minerals do not correspond to their composition and structure.
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False. They do.
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What results in minerals that have different colors but otherwise identical physical properties?
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The presence of minute amounts of some elements in minerals.
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What determines the hardness and cleavage of a mineral?
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The type of atomic bond and the distance between bonded atoms or ions determine hardness and cleavage of a mineral. Covalent bonds are stronger that ionic bonds, and van der Waals forces are the weakest. Covalent bonds are strongest if atoms are closer together; ionic bonds are relatively stronger if the electrical charges on their ions are increased.
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What are the most important minerals?
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Minerals are most important if they are common in rocks, provide essential resources, or both. More than 4000 minerals have been identified, but only a few dozen are important as rock-forming mineral, because only 12 of the 89 naturally occurring elements compose 99.7 percent of Earth’s crust.
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What are the most abundant elements in the crust?
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Silicon and oxygen are the most abundant elements in the crust, and bonded with other elements, form silicates, the principle rock forming minerals.
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When do elemental substitution occur?
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Elements with similar ionic charge, size, or both substitute for each other within mineral structures. These substitutions cause minor changes in crystal structure that define groups of related minerals. Among the silicate minerals, the most important substitutions are Al 3+ for Si 4+ and the related interchange of K+, Na+, and Ca 2+ in the feldspar group, and the exchange of Mg 2+ and Fe 2+ for each other in the olivine, pyroxene, amphibole, and biotite groups.
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Most economically valuable metals are processed from what?
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Nonsilicate ore minerals, especially oxide and sulfide minerals.
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What causes plates to move across the Earth’s surface?
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tidal forces drive plate motions
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Olivine has the chemical formula
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(Mg,Fe)2SiO4
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Rates of seafloor spreading today are on the order of
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centimeters per year
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Which is an example of a divergent plate boundary?
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East African Rift
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The lithosphere
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is made of the crust and the uppermost mantle.
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One of the fastest geologic processes is
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ground breaking during earthquake
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n and Magnesium are similar in size and both have a +2 charge. Therefore we would expect
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Iron and Magnesium to substitute for each other within the crystal structure of minerals
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A mineral that is made of only one element is
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diamond; hardest as well
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What type of minerals dissolves best in water?
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ionically bonded minerals
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What is the chemical composition of graphite and diamond?
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Carbon
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At the Earth's surface, heat is lost mainly though
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radiation
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which of the following subduction zones subducts the smallest plate?
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Central America subduction zone
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the lower mantle is
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mostly solid
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Which mineral is an example that exhibits metallic bonds
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gold
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Which mineral is an example that exhibits ionic bonding?
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calcite
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In quartz
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silicon is bonded covalently to oxygen
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he most abundant element in the whole solid earth is
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iron
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Element substitution in minerals is most likely when
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the two elements have the same charge and size
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TEM stands for
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Transmission electron microscope
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plagioclase is a
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a silicate
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olivine is a
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a silicate
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the inner core is
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solid
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How and where do rocks form?
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Most natural rocks are aggregates of mineral grains. Many rocks originate from observable processes that take place at Earth’s surface. Rocks that are not related to observable surface processes arise from processes active within Earth.
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How do we classify rocks?
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Rocks can be classified descriptively or genetically. The three principal rock types – igneous, sedimentary, or metamorphic – are defined genetically, according to the processes that form them.
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What are sedimentary rocks?
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Sedimentary rocks are made up of minerals derived from the physical disintegration or chemical weathering of preexisting rocks. Clastic sedimentary rocks contain sedimentary particles of weathered rock cemented by minerals that precipitate from water. Chemical sedimentary rocks are intergrown mineral aggregates. Biological components may be significant constituents of some sedimentary rocks.
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What are igneous rocks?
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Igneous rocks form from molten lava on the surface (volcanic, or extrusive, rocks) or from magma that remains and solidifies below ground (plutonic, or intrusive, rocks).
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What are metamorphic rocks?
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Metamorphic rocks form when minerals in preexisting rocks change in response to temperature, pressure, fluid composition, or all three.
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How are the rock classes related to one another?
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The three rock classes are linked through processes that convert the materials in one class of rock into new rocks of the same or a different class. This series of processes is referred to as the rock cycle. Despite the changes of individual rocks undergo, the chemical composition of Earth remains essentially constant.
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What is a large-scale driving force in the rock cycle?
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Plate tectonics.
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what are the two general kinds of igneous rocks
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plutonic and volcanic
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An example of a rock formed by internal processes is
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conglomerate formed from river sediments
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Sedimentary rocks contain the ________ products of other rocks
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weathering
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Which condition is not important when precipitating new mineral crystals from dissolved sediments?
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duration the sediments are in solution
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What are igneous processes?
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Igneous processes involve the melting of rock to form magma and the solidification of magma into new rock. Igneous products form when magma crystallizes below Earth’s surface or erupts as lava and other materials, like volcanic ash and pumice onto Earth’s surface.
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How are igneous rocks classified?
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Composition (minerals present) and texture (crystal size) are used to classify and name igneous rocks. Ultrmafic, mafic, intermediate, and felsic are compositional catergories for magma and igneous rocks. Light colored silicate minerals dominate in silica-rich felsic rocks, whereas darker silicate minerals form mafic rocks.
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Where do igneous rocks appear in a landscape?
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Plutonic rocks at Earth’s surface are exposed when erosion removes the rocks that originally covered the solidifying magma. Once plutonic rocks are exposed to view, the resulting landforms display a variety of sizes and shapes corresponding to the processes of intrusion and how erosion exposed the rocks.
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What do volcanic rocks include?
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Volcanic rocks include lava flow, pyroclastic-fall deposits, and pyroclastic-flow deposits.
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What determines the size and shapes of volcanoes?
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Different magma compositions and types of eruptions, and varying proportions of lave flow to pyroclastic deposits.
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How do calderas form?
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Calderas form when volcanoes collapse into shallow magma chambers that partially drain during eruptions.
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When do rocks melt?
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Rocks melt gradually as the melting temperatures of their constituent minerals are exceeded.
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How does pressure affect melting temperature?
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At higher pressures, rocks melt at higher temperatures. This means that very hot rocks rising from great depth will melt as pressure decreases provided that temperature remains high.
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How does water content affect melting temperature?
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Increasing water content in rock decreases the melting temperature. Melting can be induced, therefore by adding water to hot rock at high temperature.
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Where does magma form?
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Magma forms only where unique circumstances exist that permit melting to occur in the mantle or lower crust.
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When does partial melting occur?
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Partial melting of the mantle happens where rising mantle remains hot but is exposed to decreasing pressure at divergent plate boundaries and hot spots. Partial melting of the mantle also occurs due to the addition of water from metamorphic reactions during plate subduction at convergent plate boundaries.
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What makes igneous rock compositions so diverse?
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Melting different types of rock produces magmas of different compositions. The extent to which the rocks melt also determines the composition of the magma. Two or more magmas may mingle to produce a hybrid magma with a new composition. Rocks surrounding magma may partly melt and assimilate into the liquid to change the overall composition of the magma.
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How can magma of one composition form from magma of a different composition?
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Magma of one composition can form from magma of a different composition by fractional crystallization. No single mineral composition is exactly that of the whole magma, so crystallization of a fraction of the magma changes the composition of the remaining melt. If the liquid melt separates from the crystals then a new magma composition results.
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Gas content and viscosity affect what?
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Affect volcanic phenomena and volcanic landforms; those are two properties of magma.
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What is gas content?
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Gas content determines how explosive eruptions will be and the relative proportion of lave flows and pyroclastic deposits that eruptions will produce. More gas-rich magmas are more explosive.
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What is viscosity ?
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Viscosity determines whether lava flows are thin and widespread, or thick and short. Lower viscosity produces more fluid flows.
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How are gas content and and viscosity related to silica content?
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Viscosity and gas content are in large part determined by magma composition, and both properties increase with increasing silica content.
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Why don’t all magmas erupt?
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When rocks partially melt, the resulting liquid magma is less dense than the remaining solids and rises. If however, the magma encounters less dense rock as it ascends toward the surface, then the magma stalls and crystallizes. Rock temperature decreases as magma moves near the surface. If magma does not rise quickly, then its heat is conducted to surrounding rocks and the melt cools and crystallizes before it can erupt on the surface.
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lava at Kilauea volcano in Hawaii moves down slope at speeds of ________ meters per second.
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1 to 10
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Which mineral is not common in the igneous rock exposed at Yosemite National park
Which mineral is not common in the igneous rock exposed at Yosemite National park Which mineral is not common in the igneous rock exposed at Yosemite National park |
calcite
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A student on a field trip in Yosemite National Park examines a piece of rock under a microscope and sees tiny crystals of olivine, pyroxene, and plagioclase feldspar. What type of rock is it?
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basalt
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Which of the following causes the formation of large crystals such as pegmatite?
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high fluid content of magma
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What is weathering?
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Weathering is the interaction of the geosphere with the atmosphere, hydrosphere, and biosphere.
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What is physical weathering?
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Physical weathering disaggregates rocks by mechanical means. The most effective agent of physical weathering is the freezing and thawing of water. Other processes include salt weathering, cracks formed by temp-induced expansion and contraction, and tree roots growing in rocks.
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What is chemical weathering?
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Chemical weathering occurs when minerals react with water and oxygen. The two products of chemical weathering are ions dissolved in aqueous solutions and new minerals formed by hydrolysis and oxidation.
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What is clastic sediment?
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Clastic sediment consists of the minerals and rock fragments remaining from physical weathering and newly formed mineral grains produced by chemical weathering.
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What is chemical sediment?
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Chemical sediment consists of minerals precipitated from water. The ions composing these minerals are generated mostly by chemical weathering reactions.
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How do hard sedimentary rocks form? Name important mineral cements.
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Strong, hard sedimentary rocks form when cementing minerals precipitate in the spaces between sediment grains. Calcite, quartz, clay minerals and hematite are the most important mineral cements.
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The three ingredients of sedimentary-rock texture does NOT include
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the mineralogy of the grains
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What two, easily observed characteristics are used to name sedimentary rocks?
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grain size and composition
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The direction of moving water and air currents that transport sediment can be determined by the study of
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cross-beds
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Limestone generally indicates what type of environment ?
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shallow ocean
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A conglomerate is characterized by
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rounded pebbles cemented together
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Foliation in a metamorphic rock is
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the alignment of minerals with the long axis perpendicular to the principal stress direction
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mud-cracks are useful in the study of sedimentary environments because
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they can tell you which way is up
2. they can tell you which way is down 3. they can tell you about the environment that they formed in |
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The rock Gneiss form by metamorphosis of
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Granite
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What is foliation?
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the parallel orientation of minerals in a rock
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Contact metamorphism is due to
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high temperatures and relatively low pressures
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Regional metamorphism is characterized by
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rock transformations over large regions
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What are useful index minerals
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minerals that exist over a small range of metamorphic conditions
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Metamorphic rocks form within the Earth’s crust. How do they get to the surface of the Earth?
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by uplift and erosion
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What is the role of fluids in metamorphism?
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they speed up metamorphic reactions
2. they change the composition of the rocks 3. they can deliver some ions and take away others |
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Metamorphism affects
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any igneous, sedimentary or metamorphic rocks
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Foliation in a metamorphic rock is
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the alignment of minerals with the long axis perpendicular to the principal stress direction
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mud-cracks are useful in the study of sedimentary environments because
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they can tell you which way is up
2. they can tell you which way is down 3. they can tell you about the environment that they formed in |
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The rock Gneiss form by metamorphosis of
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Granite
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What is foliation?
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the parallel orientation of minerals in a rock
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Contact metamorphism is due to
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high temperatures and relatively low pressures
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Foliation in a metamorphic rock is
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the alignment of minerals with the long axis perpendicular to the principal stress direction
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Regional metamorphism is characterized by
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rock transformations over large regions
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mud-cracks are useful in the study of sedimentary environments because
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they can tell you which way is up
2. they can tell you which way is down 3. they can tell you about the environment that they formed in |
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What are useful index minerals
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minerals that exist over a small range of metamorphic conditions
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The rock Gneiss form by metamorphosis of
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Granite
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Metamorphic rocks form within the Earth’s crust. How do they get to the surface of the Earth?
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by uplift and erosion
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What is foliation?
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the parallel orientation of minerals in a rock
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What is the role of fluids in metamorphism?
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they speed up metamorphic reactions
2. they change the composition of the rocks 3. they can deliver some ions and take away others |
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Contact metamorphism is due to
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high temperatures and relatively low pressures
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Metamorphism affects
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any igneous, sedimentary or metamorphic rocks
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Regional metamorphism is characterized by
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rock transformations over large regions
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What are useful index minerals
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minerals that exist over a small range of metamorphic conditions
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Metamorphic rocks form within the Earth’s crust. How do they get to the surface of the Earth?
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by uplift and erosion
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What is the role of fluids in metamorphism?
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they speed up metamorphic reactions
2. they change the composition of the rocks 3. they can deliver some ions and take away others |
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Metamorphism affects
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any igneous, sedimentary or metamorphic rocks
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High grade metamorphic rocks can contain the following minerals:
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Silimanite, Garnet, Pyroxene
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In the rock cycle weathering
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creates sediment
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Which of the following rocks form from molten material cooling and solidifying within the Earth’s crust
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plutonic
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Molten rock within the Earth is called
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magma
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Which word is a synonym of plutonic?
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intrusive
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Where are contact metamorphosis rocks formed?
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next to lava flows or igneous intrusions
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Contrast volcanic rock and sandstone
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Sandstone's crystal cement is made of minerals precipitated out of water, while volcanic rock's crystals formed from molten rock
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Mantle rocks can melt due to:
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addition of water
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Rocks originating from eruption of molten material at the surface are called ________ rocks
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volcanic
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student on a field trip in Yosemite National Park examines a piece of rock under a microscope and sees tiny crystals of olivine, pyroxene, and plagioclase feldspar. What type of rock is it?
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basalt
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A synonym of volcanic is
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extrusive.
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A synonym of plutonic is
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intrusive.
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Volcanoes are present at convergent plate boundaries because
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water is carried down with the subducting plate and causes the mantle to melt.
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When a magma cools which mineral will crystallize at the highest temperature
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olivine
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a pyroclastic rock is
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a rock made up of pumice, crystals and ash
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The sedimentary rock sequence of sandstone, shale, limestone (bottom to top) is often found
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at sea shores
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Trubidity currnts travel at speeds of
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meters per second
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Consider a diagram of Depth (Y axis) vs. Temperature (X Axis). When magma intrudes the crust what happens to the geothermal gradient in this type of diagram
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the geothermal gradient slopes less steeply
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Quartzite is the result of metamorphism of
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sandstone
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Gneiss is a metamorphic rock of what grade
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high
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When dolomite gets metamorphosed
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CO2 is released
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which statement is correct?
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metamorphic reactions take place faster at high temperature
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When muscovite gets metamorphosed what happens
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water is formed
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dunes migrate because of
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erosion and deposition of sediment
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What are the two types of weathering
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physical and chemical
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Chemical weathering requires the presence of
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water
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In the Sandia Mountains, New Mexico what type of weathering is dominant
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physical
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