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Definition of Geology

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the science that deals with the earth's physical structure and substance, its history, and the processes that act on it.

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Definition of Historical Geology

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is a discipline that uses the principles and techniques of geology to reconstruct and understand the geological history of Earth

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What are geologic resources?

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are the basis of industrial development and improvement of human life styles. Geological resources include all types of resources extracted from earth's crust. mineral resources: metals, fertilizers, minerals, petroleum, construction water resources: lakes, rivers

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geologic hazards

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is an extreme natural events in the crust of the earth that pose a threat to life and property, for example, earthquakes, volcanic eruptions, tsunamis (tidal waves) and landslides

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Catastrophism

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the idea that earth has been dramatically affected by short-lived, global events ex. Noah and the arch; contrasts with uniformitariansim

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Uniformitarianism and James Hutton

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James Hutton is known as the founder of modern geology. Also known for his theory of uniformitarianism which is the belief that geological forces at work in the present day—barely noticeable to the human eye, yet immense in their impact—are the same as those that operated in the past.

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Geologic Time

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assign fairly accurate dates to events in Earth's history

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Absolute Age Dating

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relies on the decay of naturally occurring radioactive isotopes

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Relative Age Dating

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was used to come up with the geologic time scale before the technology existed to allow us to perform absolute age dating ex. relationships in age between family members

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superposition

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stuff on bottom older stuff on top younger

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Principle of Faunal succession

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fossil organisms succeed one another in a definite and determinable order and therefore any time period can be recognized

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Scientific Inquiry

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asking questions in the field of science, science assumes the natural world is consistent and predictable, the goal of science is to uncover patterns in nature

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hypothesis

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a tentative or untested explanation

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theory

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a well tested and widely accepted view that the scientific community agrees best and explains certain observable facts

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What are the four spheres of the earth system?

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The earth is a planet that is small and self contained comprised of four spheres hydrosphere: h20 portion atmosphere: gas that surrounds the earth biosphere: plant and animal geosphere: largest of 4 spheres Earths spheres are separate but interacting

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Earth system science

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aims to study earth as a system composed of interacting parts or subsystems uses interdisciplinary approach to solve global environmental problems

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cycles within the earth system

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-hydro -nitrogen -carbon -rock process driven by: energy from the Sun, heat from the Earth's interior

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nebular hypothesis

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rotating cloud called the solar nebula composed of hydrogen and helium nebula began to contract about 5 billion years ago assumes a flat disk shape with the protosun at the center inner planets began to form from metallic and rocky substances larger outer planets began forming from fragments of ice particles (H20, C02) -contraction and rotation forms rotating disk, things based on density are pulled apart

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formation of layered structure of Earth

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-heavy metals (greater density) sank to the center of the proto-earth -molten rock rose to produce a primitive crust -chemical segregation established the three basic divisions of the Earth's interior -primitive atmosphere evolved from gases in the Earth's interior

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Earth's layers defined by chemical composition

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crust, mantle, core 4 elements make up 90% of earth (iron, oxygen, silicon, magnesium) layers defined by physical properties

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lithosphere

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strong rocky rigid outer shell of the solid earth including the crust and the uppermost part of the mantle

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asthenosphere

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weak ductile layer of the mantle beneath the lithosphere deforms to accommodate the motions of the overlying plates

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mesosphere

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liquid shell

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inner and outer core

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solid innermost sphere consisting of a molten outer core and a solid iron-nickel metallic inner core

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Mantle

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middle layer of the Earth, made of mostly solid rock.

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What three things have helped us understand the interior of the Earth?

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Seismology: the study of wave propagation through the Earth meteorites-can tell how planet was formed with those kind of rocks Magnetism: the magnetic field of the Earth generated in the outer core

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What about the Crust?- (Earth's Surface)

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Thin and Rocky composed of oceanic crust and continental crust

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Oceanic Crust

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mostly comprised of magnesium and iron approximately 7km thick -new oceanic crust is created at MOR's and destroyed at trenches (subduction)

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Continental Crust

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-comprised of silica and feldspars -these rocks are less dense than oceanic crust so they float -continents are comprised of relatively thin layers of sedimentary rocks that sit atop craton

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surface of the Earth

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-Ocean Floor -continental Margins -seafloor adjacent to continents -includes the continental shelf, continental slope and the continental rise deep ocean basins abyssal plains, oceanic trenches, and seamounts Oceanic Ridge system -most prominent topographic feature on Earth composed of igneous rock that has been fractured and uplifted the rock cycle

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James Ussher

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Anglican church Bishop who was memorable for his chronology of the Old Testament. Dated the creation of the universe at 4004 bc

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Minerals

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solid naturally occurring inorganic substance with definite physical properties and variable chemical composition

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Rocks

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are composed of minerals, the mineral composition and texture (size shape and arrangement of mineral grains) reflects the conditions under which a rock formed

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Igneous Rock

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-formed from the volcanic activity, cooling and solidifying of liquid hot magma/lava -do not find fossils in igneous rock, life destroyed by heat generated

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Difference between a rock and a mineral

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A mineral is a naturally-occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. A rock is a naturally occurring aggregate of minerals and/or mineraloids. Rocks do not have a definite chemical composition.

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intrusive

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-slow cooling large crystal grains (coarse grained)

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extrusive

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-quick cooling, smaller crystal grains (fine grained)

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Metamorphic Rock

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formed by transformation of previous rock types -driving forces are heat and pressure contact metamorphism- generated by heat and pressure, hydro-thermal fluids and igneous intrusions regional metamorphism- two continents shoving up against each other, when plates hit each other gives off friction which generates heat and changes rocks (mountain building events)

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Sedimentary Rock

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formed by the compaction and lithification of broken pieces from other rocks -pieces broken off by physical and chemical weathering -deposited by wind, water, and ice in beds comprised about 75% of rocks on the surface examples: sandstone (from grain), shale (from mud)

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What elements are most abundant in the Earth's crust?

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O, Oxygen 45.2% by weight Si, Silicon 27.2% Al, Aluminum 8.0% Fe, Iron 5.8% Ca, Calcium 5.1% Mg, Magnesium 2.8% Na, Sodium 2.3% K, Potassium 1.7% Ti ,Titanium 0.9% H, Hydrogen 0.14% Mn, Manganese 0.1% P, Phosphorous 0.1%

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Uses for common minerals (hematite, quartz, halite, sulfides... etc)

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Hematite: iron for metalworks (steel) Quartz: glassware, electronics Halite: salt for food, deicing etc. Sulfides: chemicals, fertilizers

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What is a polymorph and what causes polymorphism in minerals?

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Two or more minerals that contain the same chemical composition but differ in their atomic arrangement and crystal structure. A well-known example is Diamond and Graphite Formation at different pressure and temperature conditions

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Mineral Classes- what are the most common in the Earth's crust?

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Silicates, Oxides, Sulfides,

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Silicates

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This is the largest group of minerals. Silicates are made from metals combined with silicon and oxygen. There are more silicates than all other minerals put together. mica is a member of this group.

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Oxides

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Oxides form from the combination of a metal with oxygen. This group ranges from dull ores like bauxite to gems like rubies and sapphires. magnetite is a member of this group

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Sulfides

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Sulfides are made of compounds of sulfur usually with a metal. They tend to be heavy and brittle. Several important metal ores come from this group

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Steno's laws

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Law of Superposition Law of Original Horizontality Law of Cross-Cutting Law of Lateral Continuity

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Law of Superposition

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In a sequence of rock strata, the oldest layer will lie below or underneath the youngest.

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Law of Original Horizontality

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Layers of sediment, such as you would have in the bottom of a lake, or the ocean, are deposited by gravity into flat layers.

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Law of Cross-Cutting

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If a rock layer is cut by a fault or igneous intrusion, the rock that is cut must be older than the layer that cuts it.

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Law of Lateral Continuity

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Rock layers will extend outwards until the environment that produced them changes.

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Three types of atomic bonds

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The three types of chemical bonds are Ionic bonds, Covalent bonds, and Polar covalent bonds.

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In what THREE ways can minerals form?

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They can form when magma crystallizes They can also form due to weathering of existing rocks, or they can form by precipitating dissolved chemicals from water During the process of "metamorphosis" -- when rocks of one type gradually get transformed into another kind of rock.

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Diagnostic Properties for the I.D. of minerals

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distinctive physical properties such as color, crystal form, cleavage, luster, streak

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Why are mid ocean ridges called "ridges" and trenches called "trenches?"

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MOR- ridges are underwater mountain belts formed where plates are separating and rise above the adjacent ocean seafloor Trenches are deep depressions in the seafloor caused by subducting plates at convergent margins

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What evidence was used to bolster the argument of continental drift?

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Sea Floor Spreading: age of the oceanic crust becomes older away from the ridges Hot Spot volcanic islands like Hawaii Like faunas & floras (fossil animals and plants) found on now widely separated continents

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When was lack of evidence rectified and by whom?

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J. Tuzo Wilson in 1963: Wilson in 1963 with his introduction of hotspots. He accepted the idea of sea floor spreading by noticing the increase in age of island rocks with increased distance from the Mid-Ocean Ridge.

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Who first developed the theory of Continental Drift?

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Continental drift was a theory that explained how continents shift position on Earth's surface. Set forth in 1912 by Alfred Wegener, a geophysicist and meteorologist, continental drift also explained why look-alike animal and plant fossils, and similar rock formations, are found on different continents

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How many major/minor plates make up the Earth's surface?

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There are eight large plates and nine smaller ones. Notice that the major plates include both continents and oceans.

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Name the last 2 supercontinents. Which is older? Which is younger?

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Rodinia formed about a billion years ago. it was big, was probably located almost entirely south of the equator, and began to break apart roughly 550 million years ago. Pangaea, last of Earth's supercontinents. Pangaea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 300 million years ago

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What are the three plate boundary types? What features do you see associated with each?

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There are three kinds of plate tectonic boundaries: divergent, convergent, and transform plate boundaries.

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divergent plate boundary

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The Mid-Atlantic Ridge is a classic example of this type of plate boundary a divergent boundary is a boundary where two tectonic plates are moving away from one another. most often takes place at ocean ridges. divergent boundaries can also form on continents. When this happens, a line of volcanoes emerges.

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convergent plate boundaries

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In the case of plate tectonics, the two objects coming together are large plate-like pieces of the Earth's crust. As these two plates push against each other, one is ultimately forced down beneath the other. As the earth above the two meeting plates rise, forming spectacular mountain ranges. A parallel oceanic trench typically forms just off the shore, as one plate descends deep into the Earth's core. a number of small and large earthquakes are common near convergent boundaries

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transform plate boundaries

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two plates slide against each other in a sideways motion. Two massive plates pushing against one another is that massive amounts of energy build up. Occasionally this energy is released suddenly in the form of large earthquakes.

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Paleomagnetism

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magnetic minerals in rocks: Paleo=old/ancient, magnetism=magnets iron grains act as compass needle and point north when they solidify take idea of paleomagnetism and apply it to rocks all over earth funding + sonar technology= mapping of seafloor

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What two factors allowed us to study the ocean floor at a previously unprecedented level?

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Acoustic mapping (sonar) of the seafloor Magnetic reversals recorded in oceanic crust

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What global conflict preceded these advancements?

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World War II

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What evidence (or lack thereof) did opponents of plate tectonics counter the theory's stipulations with?

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Plates were not strong enough to move through across the viscous mantle layer

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Harry Hess

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came up with hypothesis for seafloor spreading upwelling of mantle at oceanic ridges lateral spreading of seafloor away from ridge crest new crust created at ridges crust is drawn back into the mantle at deep ocean trenches

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what branch of geology focuses on the study of rock layers

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-historical

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fairly accurate dates to events in geologic history

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absolute age dating

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the birth of modern geology is marked by the paradigm shift to

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uniformitarianism

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three most common chemical elements found in the crust

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iron h20 silica

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what are some reasons that collecting data might be difficult for geology

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-processes may occur at slow rates, events may be rare, evidence may be destroyed, evidence may be inaccessible

Geology Test 1: chapters 1-3 – Flashcards

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