204 Cards in this Set
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What is Geology?
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The study of the Earth, including our planet's composition, behavior, and history.
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What is Physical Geology?
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The study of physical features of the earth's surface.
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What is uniformitarianism?
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The belief that Earth's past geological changes can be fully explained by processes taking place now.
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What is the concept of uniformitarianism and why is it important ?
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The present is the key to the past. Uniformitarianism is important because it helps geologists understand how earth worked in the past
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Geologic Time
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The span of time since the formation of the Earth.
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How old is the Earth?
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4.57 Billion years-old
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How is the age of earth determined?
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By the decay of long-lived radioactive isotopes of elements that occur naturally in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements.
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Magnitude of Geologic Time
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Involves vast times- millions or billions of years (Geologic process may be gradual or rapid)
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The Nature of Scientific Inquiry
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Science assumes the natural world is consistent and predictable, goal of science is to discover patters in nature and use the knowledge to make predictions, scientists collect data through observation and measurements.
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Hypothesis
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A proposal intended to explain certain facts or observations
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Theory
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a well-substantiated explanation of some aspect of the natural world
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Scientific Methods
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a series of steps followed to solve problems, including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions
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Subsystems of the Earth
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The Atmosphere, The Crust, The Mantle, The Core, The Lithosphere and Asthenosphere
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Geology and its effects on our lives
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Global Warming, Tsunamis, Earthquakes, Economy, Resources
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Origin of Planet Earth
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The Big Bang Theory
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Nebular theory
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theory that the sun and the planets condensed out of a spinning cloud of gas and dust
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Solar Nebular Hypothesis
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a giant cloud of dust and gas collapsed (about 5 billion years ago this happened and created our solar system)
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Origin of the Solar System
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Solar Nebular Hypothesis
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Inner Core
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Depth of 5,155 km to 6,371 km, is a solid iron-nickel alloy that may reach a temperature of over 4,700 degrees Celsius
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Outer Core
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Depth of 2,900 km and 5,155 km deep, is a liquid iron alloy (because of high temperature), a layer of molten iron and nickel that surrounds the inner core of Earth
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The Mantle
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2,885-km-thick layer surrounding the core, It is the intermediate layer. The outermost part is solid and the deepest one is formed by molten rocks
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Upper Mantle
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depth of 400 km, layer of the earth that is a plastic like solid yet flows under pressure
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Lower mantle
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Extends to core; does not melt b/c of high pressure
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Asthenosphere
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The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
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Lithosphere
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the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle
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Crust
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the thin and solid outermost layer of the Earth above the mantle
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Oceanic Crust
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7 to 10 km thick
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Continental Crust
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35 to 40 km thick
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Plate Tectonics Theory
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Theory that great slabs or plates of Earth's outer layer float on a hot, semi-molten mantle. All plates are moving slowly and have rafted continents to new positions over time.
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Divergent Boundaries
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(a.k.a. normal faulting) is a place where 2 plates move apart. Most of these types of boundaries occur at the mid-ocean ridge. On land, this boundary is called a rift valley, such as the Great Rift Valley in East Africa and the Rio Grande in Texas.
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Convergent Boundaries
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(a.k.a. reverse fault) is a place where 2 plates come together. At places where oceanic crust converges, the denser oceanic crust will dive under the other (subduction). At places where oceanic crust and continental crust converge, the denser oceanic crust will dive under (subduction) the…
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Continental-continental convergent plate boundaries
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areas of great compression and mountain building
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Continental-oceanic plate convergent boundaries
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Denser oceanic slab sinks into asthenosphere, along descending plate partial melting of mantle rock generates magma
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Oceanic-oceanic convergent plate boundaries
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When two oceanic slabs converge, one descends beneath other, Often forms volcanoes on ocean floor
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Divergent plate boundaries
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occur when two oceanic plates move apart from one another. Results in oceanic ridges. Magma flows into the resulting cracks oceanic ridges under the surface of the ocean.
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Mid-oceanic ridge
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The longest mountain range in the world; all along the center of the Atlantic Ocean; formed by active volcanoes through sea floor spreading
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Rock Types
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sedimentary, igneous, metamorphic
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Rock Cycle
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sequence of events in which rocks are formed, destroyed, altered, and reformed by geological processes
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Igneous Rocks
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rocks formed by the cooling of molten rock (either magma or lava)
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Sedimentary Rocks
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Rocks formed from the weathering, erosion, deposition, and compaction of other rocks
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Metamorphic Rocks
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formed from preexisting rock subjected to heat and pressure (rock is solid, but minerals break down, form, change shape)
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Wegner's hypothesis of continental drift
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suggested a super continent (Pangaea) existed until the Mesozoic era, then broke apart to form the continents we see today- these continents drifted from each other
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Evidence for Continental Drift
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the fit of the continents, locations of past glaciations, the distribution of equatorial climatic belts, the distribution of fossils, and matching geologic units
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Paleomagnetism
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The study of the alignment of magnetic minerals in rock,specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock requires during formation.
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The Earth's magnetic field
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is believed to arise from currents in the Earth's core.
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Seafloor Spreading (the beginning of a revolution)
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The process that creates new sea floor as plates move away from each other at the mid-ocean ridges
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Evidence for new crust
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Magnetic Anomalies
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Plate Boundaries
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the edge of a tectonic plate
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Plate tectonics
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the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle
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Hot spots
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areas of volcanic activities that result from plumes of hot solid material that have risen from deep inside earths mantle
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Birth and death of plates
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Continental Rifting and collision
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Mantle convection
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The driving force of plate tectonics
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What is matter?
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anything that has mass and takes up space
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What is matter composed of?
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All matter is composed of mass
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Types of matter
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Solids, liquids, gas, plasmas.
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How do we know if something is a mineral?
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Is it a solid? Is it inorganic? Is it formed in nature? Does it have a crystalline structure?
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What is a rock?
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A mixture of minerals, rock fragments, volcanic glass, or other natural materials.
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Crystalline
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consisting of or containing or of the nature of crystals
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What is amorphous?
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No definite structure
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What is an element?
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many of the SAME kind of atom
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What is an atom?
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the smallest particle of an element
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Structure of atoms
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Neutrons, Electrons, Protons
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Neutrons
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the particles of the nucleus that have no charge
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Electrons
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negatively charged particles
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Protons
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Positively charged particles
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How is an atom's identity determined?
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by number of protons in atom's nucleus
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Atomic Number
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Number of Protons
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Atomic Mass Number
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Number of Neutrons and Electrons
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Types of Chemical Bonds
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Ionic, Covalent, Metallic, van der Waals bonding
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Ionic bonds
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formed when one or more electrons are transferred from one atom to another
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Covalent bonds
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form when electrons are shared between atoms
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Metallic bonds
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consist of the attraction of the free-floating valence electrons for the positively charged metal ions
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van der Waals bonding
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sheets of covalently bonded atoms held together by weak electrostatic electrical forces, very weak bonds
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Isotopes
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atoms of the same element that have different numbers of neutrons
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Mineral Structure
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naturally formed, inorganic, solid, definate crystalline structure
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Polymorph
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One of two or more alternative possible crystal structures for a single chemical compound; for example, the minerals quartz and cristobalite are polymorphs of silica (SiO2).
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Does internal structure determine the external shape?
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yes
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Halite structure
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isometric
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Properties of minerals
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color, luster, hardness, streak, density, crystal shape, cleavage and fracture, and special properties (such as magnetism & smell)
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Is color a good diagnostic feature?
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No
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Moh's hardness scale
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a scale ranking ten minerals from softest to hardest; used in testing the hardness of minerals
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mineral fracture
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tendency of some minerals to break unevenly along curved or irregular surfaces
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mineral cleavage
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determined by a minerals structure is the tendency to split along definite planes
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Specific Gravity
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ratio of a mineral's weight compared with the weight of an equal volume of water
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Rock Forming Minerals
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Minerals that make up most of the rock's crust. 20 minerals make up the earth's crust. Ex.: Granite is made of quartz, feldspar, hornbelnde, and mica.
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Silicates
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rocks made of compounds of silicon and oxygen
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Most abundant elements in the continental crust
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silicates
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Silicon-oxygen tetrahedron
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a structure composed of four oxygen atoms surrounding a silicon atom that constitutes the basic building block of silicate minerals
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Silica groups
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Independent tetrahedra, single chains, double chains, sheet silicates
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Common silicates
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Quartz and feldspar
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Silica tetrahedron
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Basic building block of silicate minerals, made up of four oxygen atoms and 1 silicon aton
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Ferromagnesian
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subgroup of silicate minerals that form rocks; based on presence of iron, magnesium, calcium etc. Olivine
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Nonferromagnesian
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do not have iron and magnesium, feldspar
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Non-silicate mineral groups
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Carbonate, Halite, native, oxides, sulfates, and sulfides
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Types of Igneous rocks
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intrusive extrusive
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Intrusive Igneous rocks
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rocks formed from the cooling a magma beneath the earth's surface
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Extrusive Igneous rocks
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rocks formed from molten lava that hardens on the earth's surface
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What is Magma?
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Magma is molten, hot, liquid rock under the Earth's surface.
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Properties of igneous rocks
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Magmatic consolidation, both crystalline and non-crystalline, non-porous, poorly eroded, no fossils 40-80% silica
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Aphanitic
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Rapid cooling at earth's surface results in tiny mineral crystals that can only be seen under a microscope.
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Phaneritic
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coarse-grained, crystals are large enough to be seen w/out a microscope, formed by slow cooling (intrusive)
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How are crystal sizes related to cooling rates?
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the slower they cool, the larger the crystals are
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Volcanic Igneous rocks
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created when rocks are melted through enormous amounts of heat and pressure and liquid magma is forced through other rocks to erupt on Earth's surface as lava
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Glassy texture
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a term used to describe the texture of certain igneous rocks, such as obsidian, that contain no crystals
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Pyroclastic texture
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an igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent eruption
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Pegmatitic
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Very large crystals formed by extremely slow cooling, or in the presence of water.
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Felsic
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Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.
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Intermediate igneous rocks
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midway between felsic and mafic ends of the scale.
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mafic
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describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color
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How does silica content vary from Felsic to Ultramafic?
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Felsic- highest silica content, Ultramafic- lowest silica content
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Felsic viscosity
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highest viscosity
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Ultramafic viscosity
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lowest viscosity
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How does silica content affect viscosity?
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The more silica is in a magma the more viscous the magma will
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mafic basalts
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fine grained, pyroclastic, vesicular, Amygdaloidal
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felsic rhyolites
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SiO2=70%, Fe-Mg poor, low temp, high viscosity, formed at hot spots, continental rifts
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viscosity
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a liquid's resistance to flow
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explosivity
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rate of volcanic explosion. high rates= more dangerous
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What types of magma are more viscous?
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Felsic rhyolites
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Origin of Magma
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melting of preexisiting rock
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What is the geothermal gradient?
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The gradual increase in temp. with depth in the crust--know relation to magma
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evolution of magmas
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Felsic magma can evolve from mafic magma.
Progressive removal of mafics depletes Fe, Mg, and Ca. Remaining melt becomes enriched in Na, K, Al, and Si.
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Bowen's Reaction Series
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the simplified pattern that illustrates the order in which minerals crystallize from cooling magma according to their chemical composition and melting point
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Changing Magma Compositions
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1.filter pressing
leave mafic minerals behind
2.Assimilation
melt another rock & mix!!
3.Mixing
4.Partial melting
Only melts felsic minerals
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Crystal settling
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during the crystallization of magma, the earlier formed minerals are denser than the liquid portion and settle to the bottom of the magma chamber
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Magma Mixing
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altering the composition of a magma through the mixing of material from another magma body
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Igneous features
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dikes, sills, plutons, batholiths, laccoliths
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Weathering
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The breaking down of rocks and other materials on the Earth's surface.
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Differential Weathering
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the process by which softer, less weather resistant rocks wear away and leave harder, more weather resistant rocks behind
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Types of weathering
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mechanical weathering, chemical weathering
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Mechanical weathering
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The type of weathering in which rock is physically broken into smaller pieces
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Chemical weathering
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the process in which rock is broken down by changes in its chemical makeup
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Types of mechanical weathering
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frost wedging, unloaded/loaded pressure release, thermal expansion, biological activity and abrasion
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Types of chemical weathering
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dissolution, hydrolysis, oxidation, hydration
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Rates of weathering
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depend on climate, elevation, and makeup of the rock
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Factors affecting weathering
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chemical weathering affected by water and temperature. mechanical affected by water, temperature and slope.
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Factors Controlling Soil Formation
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Parent material and time
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Soil horizons
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horizontal layers that reveal a soil's history, characteristics, and usefulness
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erosion
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(geology) the mechanical process of wearing or grinding something down (as by particles washing over it)
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rates of erosion
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The rate in years at which rock wears away by natural processes, such as a stream eroding its bed. Only practical for features that formed within the last 10000-20000 years.
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What controls the rate of erosion?
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human activities that remove natural vegetation such as farming, logging and construction.
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origin of sedimentary rocks
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deposited at earth's surface, temp cool, pressure low, transported by wind, water, ice, typically deposited as LAYERS or STRATA
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diagenesis
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a collective term for all the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification
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How does diagenesis change sediment into a sedimentary rock?
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by lithification
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Detrital
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sedimentary rocks made from the broken fragments of other rocks that are compacted and cemented together
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Chemical sedimentary rocks
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form when minerals are precipitated from a solution or left behind when a solution evaporates
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detrital example
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clay minerals and quartz
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Breccia
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a rudaceous rock consisting of sharp fragments embedded in clay or sand
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conglomerate
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a composite rock made up of particles of varying size
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Chemical sedimentary rock example
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limestone, rock salt
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Stages of coal formation and grades
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1. peat 2. soft coal 3. hard coal
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Sedimentary environments
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Dunes, beaches, streams, glacier deposits, etc., a geographic location characterized by environmental conditions and geological processes
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Sedimentary textures
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clastic, non-clastic
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Clastic
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texture which results when fragments of rock are lithified, discrete fragments and particles can be identified
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Non-clastic
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other textures including crystalline, amorphous, and biochemical; crystalline rocks have pattern on interlocking crystals. Discrete particles can not be seen when looking at a rock in your hand
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Explosivity factors
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the more explosive volcanoes are depends on how frequently the tectonic plates move.
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Factors affecting viscosity
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Chemical composition of magmas (more silica content=more viscous), temperature (hotter temperature=less viscous), amount of dissolved gases
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Types of Volcanic eruptions
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magmatic eruptions, Phreatomagmatic eruptions , Phreatic eruption
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Pahoehoe
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fast-moving, hot lava that has low viscosity
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Aa lava
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Slow moving, rough lava. (high viscosity)
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Lava tubes
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A natural conduit through which lava travels beneath the surface of a lava flow, they form by the crusting over of lava channels and pahoehoe flows
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Pillow Lavas
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lava that solidifies in an underwater environment and develops into a structure like a pillow
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Pyroclastic Materials
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the volcanic rock ejected during an eruption including ash, bombs, and blocks
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Ash
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the smallest lava fragment produced by a volcano.
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lapilli
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pebble like bits of magma that cool in the air
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Volcanic bombs
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A projectile of hot magma or rock that is blown from the vent during a volcanic eruption. These solidify in flight and frequently form an elongated rock of streamlined shape.
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Structure of Volcanoes
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molten rock in the asthenosphere finds weakness in the crust, creating a central vent. Secondary branches will form
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Volcano Features
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magma chamber, fissures and vents, craters, calderas
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magma chamber
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the pocket beneath a volcano where magma collects
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fissures and vents
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conduit from the magma chamber to surface; makes linear tear form magma to erupt
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volcanic craters
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a bowl-shaped opening at the top of a volcano
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caldera
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a large crater caused by the violent explosion of a volcano that collapses into a depression
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Fumarole
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a vent in a volcanic area from which fumes or gases escape
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Types of Volcanoes
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Shield; Composite Cone; Cinder Cone
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Shield Volcano
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A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava
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Composite Volcano
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a tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials
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Volcanoes impact on humans/ environment
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Dormant- rich soil from chemicals of past explosions
Active volcanoes-ash, flying molten rocks, shockwave of sound, landslides, Nuee ardentes (huge cloud of gas)
Underwater volcanoes- can cause tsunamis after eruption
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Pyroclastic flow
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The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption
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Nuee ardentes
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superheated ash/gasclouds that race down slope (about 60 mps) blast laterally from the side of cone, or collapse from a tall column of ash/gas in the atmosphere
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Lahars
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mudflows (water mixed with ash)
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Caldera formation
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formed when massive explosive eruption causes collapse of a volcano into its magma chamber
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Fissure Eruptions
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the eruption of lava from a crack in the lithosphere rather than from a central vent. columbia plateau, hawaii
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Flood basalts
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Hot spots under continents: Example: 50MA before now, vents opened near Kamploos and flood basalts accumulated in the valleys to the depth of 2400m
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Lava Domes
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inside other volcanoes, felsic magmas from melting of continental crust
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Volcanic necks
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Remains of cooled magma in the pipe of a volcano. They become exposed when the softer rock around the pipe wears away.
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Volcanic pipes
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brings magma from magma chamber towards the surface
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Plutons
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magma that stops moving before it reaches the surface and cools into mineral crystals
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Dikes
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Formed when magma squeezes across rock layers and cools (vertically).
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Sills
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Formed when magma squeezes between rock layers and cools (horizontally).
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Batholith
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large mass of intrusive igneous rock believed to have solidified deep within the earth
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Intrusive igneous rock
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rock formed from the cooling and solidification of magma beneath Earth's surface
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laccolith
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a hardened magma chamber
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Concordant
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an intrusive igneous mass that formed parallel to the bedding of the surrounding rock. Laccolith, Lopolith, Phacolith, Sill
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discordant
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an intrusive igneous mass that formed on top of the bedding or surrounding rock. batholith, dike, stock
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Hot spot locations
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above the hottest parts of the mantle
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Hot spot magma
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basaltic magma (continental hot spots also have rhyolitic debris)
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Volcanic effects on climate
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can trigger coolness in volcanic area
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Mid-Oceanic Ridges
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mountain ranges at divergent boundaries in oceanic crust, created by magma rising to Earth's surface and cooling (new lithosphere), example Mid-Atlantic Ridge
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Type of Magma associated with divergent plate boundaries?
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basaltic
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felsic rock location
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continental crust
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circum-pacific belt (ring of fire)
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belt around pacific ocean on which most composite volcanoes are located and where earthquakes occur
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mafic rock location
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derived from mantle
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Location of Volcanoes
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Most volcanoes occur along plate boundaries or at hot spots in the crust. Volcanoes can occur along a converging plate boundary where an oceanic plate is subducted into the mantle.
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Convergent plate boundaries
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Two plates colliding and creating either a mountain range (2 continental) or a subduction zone (2 oceanic), or trench (oceanic and continental)
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Types of Magma
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Basaltic magma
Andesitic magma
Rhyolitic magma
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GEO 101: Exam 3