exam 1 Flashcards
The Scientific Method
- OBSERVATION, PROBLEM, OR RESEARCH QUESTION 2. HYPOTHESIS
- EXPERIMENT AND HYPOTHESIS REVISION
- PEER REVIEW, PUBLICATION, AND REPLICATION
- THEORY DEVELOPMENT
Deductive Reasoning
Taking known truths in order to develop new truths.
Inductive Reasoning
Establishing evidence (including new observations) to infer a possible truth.
Two important aspects of science
Observation and Inference
Catastrophism
The idea that large, damaging events are the cause of most geologic events.
Principal of Uniformitarianism
Idea championed by James Hutton that the present is the key to the past, meaning the physical laws and processes that existed and operate in the past still exist and operate today.
The Rock Cycle
The process of changing rocks on Earth into different forms, namely igneous, sedimentary, and metamorphic.
Psuedoscience
A method of investigation the claims to be scientific, but does not hold up to full scientific scrutiny. Examples include astrology, paranormal studies, young-Earth creationism, and cryptozoology (i.e. the study of creatures like Bigfoot and the Loch Ness Monster).
Minerals
A natural substance that is typically solid, has a crystalline structure, and is typically formed by inorganic processes. Minerals are the building blocks of most rocks.
Falsifiable
The idea that any claim in science can be proved wrong with proper evidence.
Theory
An accepted scientific idea that explains a process using the best available information.
Sandstone
A rock primarily made of sand
Shale
A very fine-grained rock with very thin layering (fissile).
Sedimentary Rock
Rocks that are formed by sedimentary processes, including sediments lithifying and precipitation from solution.
Sediments
Pieces of rock that have been weathered and possibly eroded.
Sedimentary
Rocks
Rocks that are formed by sedimentary processes, including sediments lithifying and precipitation from solution.
Strata
Discernible layers of rock, typically from a sedimentary rock.
Theory of Plate Tectonics
The theory that the outer layer of the Earth (the lithosphere) is broken in several plates, and these plates move relative to one another, causing the major topo- graphic features of Earth (e.g. mountains, oceans) and most earthquakes and volcanoes.
Continental Crust
The layers of igneous, sedimentary, and metamorphic rocks that form the conti- nents. Continental crust is much thicker than oceanic crust. Continental crust is defined as having higher concentrations of very light elements like K, Na, and Ca, and is the lowest density rocky layer of Earth. Its average composition is similar to granite.
Alfred Wegener
first scientist to compile a large data set supporting the idea of continents shifting places over time
Mid Ocean Ridge
A divergent boundary within an oceanic plate, where new lithosphere and crust is created as the two plates spread apart. Mid-ocean ridge and spreading center are synonyms.
Magnetic Stripping
Symmetric (about the ridge) patterns of magnetism created by ocean floor rocks recording changes in Earth’s magnetic field.
Earth System Science
Geosphere, Atmosphere, Hydrosphere, Cryosphere, Biosphere
Geosphere
The solid, rocky parts of the Earth, including the crust, mantle, and core.
Atmosphere
The gases that are part of the Earth, which are mainly nitrogen and oxygen.
Hydrosphere
The water part of the Earth, as a solid, liquid, or gas.
Cryosphere
The part of the hydrosphere (water) that is frozen, found mainly at the poles.
Biosphere
The living things that inhabit the Earth
Rock cycle
A series of processes on the surface and inside Earth that slowly changes rocks from one kind to another
Magma
Liquid rock within the Earth. Forms in the crust or mantle
Igneous Rock
Rocks that are formed from liquid rock, i.e. from volcanic processes. Magma - Crystallization - Igneous Rock
On the surface of earth
Lithification
The process of turning sediment into a sedimentary rocks, including deposition, compaction, and cementation.
Meta-Morphic Rock
Rocks formed via heat and pressure which change the minerals within the rock.
asthenosphere
A ductile physical layer of the Earth, below the lithosphere. Movement within the asthenosphere is the main driver of plate motion, as the overriding lithosphere is pushed by this.
Crust
The outermost chemical layer of the Earth, defined by its low density and higher concentrations of lighter elements. The crust has two types: continental, which is the thick, more ductile, and lowest density, and oceanic, which is higher density, more brittle, and thinner.
Oceanic Crust
The thin, outer layer of the Earth which makes up the rocky bottom of the ocean basins. It is made of rocks similar to basalt, and as it cools, even become more dense than the upper mantle below.
Lithosphere
The outermost physical layer of the Earth, made of the entire crust and upper mantle. It is brittle and broken into a series of plates, and these plates move in various ways (relative to one another), causing the features of the theory of plate tectonics.
Mantle
Middle chemical layer of the Earth, made of mainly iron and magnesium silicates. It is generally denser than the crust (except for older oceanic crust) and less dense than the core.
1800 miles or 2900 km below the earths surface upper part of mantel floats under the tectonic plates
Peridotite
An intrusive ultramafic rock, which is the main component of the mantle. The minerals in peridotite are typically olivine with some pyroxene.
Core
The innermost chemical layer of the Earth, made chiefly of iron and nickel. It has both liquid and solid components.
Rotations within the solid and liquid metallic core generate Earth’s magnetic field
Outer Core
Solid
Inner Core
Liquid
Isotope
An atom that has different number of neutrons but the same number of protons. While most properties are based on the number of protons in an element, isotopes can have subtle changes between them, including temperature fraction- ation and radioactivity.
Age of Earth
4.54 ± 0.05 billion years old
Discovered by Clair Patterson in 1956, who measured the half-lives of lead iso- topes to radiometrically date a meteorite
Eons
The largest span of time recognized by geologists, larger than an era. We are currently in the Phanerozoic eon. Rocks of a specific eon are called eonotherms.
Precambrian Pe-
riod
A term for the collective time before the Phanerozoic (pre-541 million years ago), including the Hadean, Archean, and Proterozoic. Known for a lack of easy-to-find fossils
First life on Earth
3,800 million of years ago (Ma)
Phanerozoic Eon
Meaning “visible life,” the most recent eon in Earth’s history, starting at 541 million years ago and extending through the present. Known for the diversification and evolution of life, along with the formation of Pangea.
Paleozoic:
Phanerozoic Era
Meaning “ancient life,” the era that started 541 million years ago and ending 252 million years ago. Vertebrates (including fish, amphibians, and reptiles) and arthropods (including insects) evolved and diversified throughout the Paleozoic. Pangea formed toward the end of the Paleozoic.
Mesozoic: Phanerozoic Era
Meaning “middle life,” it is the middle era of the Phanerozoic, starting at 252 million years ago and ending 66 million years ago. Known as the Age of Reptiles.
Cenozoic: Phanerozoic Era
The last (and current) era of the Phanerozoic eon, starting 66 million years ago and spanning through the present.
mass extinction
A pronounced increase in the extinction rate, typically caused by significant envi- ronmental change. There have been 5 mass extinctions in geologic history, and a sixth that has been suggested to be currently occurring.
Seismographs
Instrument used to measure seismic energy
Wagners Factors of Continental
Drift
- Mesosaurus found in South Africa and North America
- Similar rocks, mountain ranges, fossils and glacial formations found along coasts
- Similar shapes among continental shelves
- Evidence of Glaciers in current warm environments
Cause of Conti- nental Drift
Convection in the mantle
SONAR
An acronym for SOund Navigation And Ranging, sonar uses sound waves to navigate and map surfaces. Sound waves created by an observer reflect off of surfaces and return to the observer. The amount of time it takes for the sound to return is a function of the distance the surface is from the observer. Bats use sonar to navigate through the dark. Ships use sonar to map the ocean floor.
Mid-Atlantic Ridge
The Mid-Atlantic Ridge is a mid-ocean ridge located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North American from the Eurasian Plate and the African Plate, north and south of the Azores Triple Junction.
Sea Floor Spreading
The process by which molten material adds new oceanic crust to the ocean floor
Epicenters
The location at the surface directly above the focus of an earthquake, typically associated with strong damage
Paleomagnetism
As a rock cools, the iron minerals within the rock align with the current magnetic field. Since the magnetic field changes (by where you are on Earth, by flips where “north”and “south” switch, and by migration of the magnetic north pole), scientists use the magnetic alignment within rocks to determine past movement or the magnetic field itself, along with the movement of rocks and plates via plate tectonics.
Magnetic moving
due to seafloor spreading the oceanic floor grows pushing and directing change to tectonic plates under the earths crust. the shifting directs changes and move- ments in earths magnetic pull
convergent
boundary
also called destructive boundaries, are places where two or more plates move toward each other. . Convergent boundary movement is divided into two types, subduction, and collision, depending on the density of the involved plates.
Lower Density
continental lithosphere
Higher Density
asthenosphere
oceanic lithosphere
denser then the continental lithosphere, when frozen denser then astenhosphere
Collision
When continental plates converge without subduction occurring
Subduction
When plates of different densities converge, the higher-density plate is pushed beneath the more buoyant plate
Obduction
when oceanic and continental plates fuse then part of a continental plate may become trapped beneath a descending oceanic plate
Transform Boundary
where the lithospheric plates slide past each other in the horizontal plane.
Dextral
Right Lateral
Sinistral
Left Lateral
Transpression
a component of compression in addition to the shearing motion. These forces build up around the area of the bend, where the opposing plates are restricted from sliding past each other. As the forces continue to build up, they create mountains
Transtension
require a fault that includes a releasing bend, where the plates are being pulled apart by extensional forces. Depressions and sometimes volcanism develop in the releasing bend
Piercing Point
A geologic feature that shows evidence of having once been continuous between two or more areas that were formerly adjacent parts of the same tectonic block.
The Wilson Cycle
The cyclical opening and closing of ocean basins caused by movement of the Earth’s plates.
Relative Dating
process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages—i.e., how many years ago the object was formed
Stratigraphy
the study of layered sedimentary rocks. This section discusses principles of relative time used in all of geology, but are especially useful in stratigraphy
Principal of Original Horizontality
States that layers of sediment are generally deposited in a horizontal position
Principal of Lateral Continuity
Within the depositional basin, strata are continuous in all directions until they thin out at the edge of that basin
principal of cross-cutting relationships
States that a fault or intrusion is younger than any rock it intrudes upon
Principle of Inclusions
objects enclosed in rock must be older than the time of rock formation
principle of fossil succession
Fossil organisms succeed one another in a definite and determinable order, and any time period can be recognized by its fossil content.
schist
Rock more metamorphosed than phyllite, to the point that mica grains are visible. Larger porphyroblasts are sometimes present.
unconformity
a period during which deposition did not occur or erosion removed rock that had been deposited, so there are no rocks that represent events of Earth’s history during that span of time at that place
nonconformity
Layered rocks on top of a non-layered rock, such as crystalline basement. type of unconformity
angular unconformity
Two rock layers that have different angles of deposition relative to horizontal. type of unconformity
disconformity
Two layered rocks that may seem conformable, but an erosional surface exist between them.
type of unconformity
Phanerozoic
“visible life,” the most recent eon in Earth’s history, starting at 541 million years ago and extending through the present. Known for the diversification and evolu- tion of life, along with the formation of Pangea.
absolute dating
Quantitate method of dating a geologic substance or event to a specific amount of time in the past.
radioisotopic dating
Using this new technology, they could assign specific time units, in this case years, to mineral grains within a rock.
radioactive isotopes
spontaneously decay over time releasing subatomic particles or energy in a process called radioactive decay. When this occurs, an unstable isotope becomes a more stable isotope of another element
Half life
The calculated amount of time that half of the mass of an original (parent) radioactive isotope breaks down into a new (daughter) isotope.
Alpha Decay
Radioactive decay where two protons and two neutrons leave the isotope.
Beta Decay
A radioactive decay process where a neutron changes into a proton, releasing an electron.
Electron Capture
A type of radioactive decay where an electron combines with a proton, making a neutron.
mass spectrometer
A device that can determine the amounts of different isotopes in a substance.
Age of the Earth
to be 4.55 billion years, give or take about 70 million (± 1.5%). The current estimate for the age of the Earth is 4.54 billion years, give or take 50 million (± 1.1%).
Zircon
ZrSiO4. Relatively chemically inert with a hardness of 8.5. Common accessory mineral in igneous and metamorphic rocks, as well as detrital sediments. Uranium can substitute for zirconium, making zircon a valuable mineral in radiometric dating.
Luminescence
light emitted by means other than burning, such as chemical or biochemical action or radiation
Fission Track
ission track dating relies on damage to the crystal lattice produced when unstable 238U decays to the daughter product 234Th and releases an alpha particle
principal of faunal science
The fossils found at any time are unique, and the fossils in layers of different ages have progressed and changed as time has moved forward. Fossils found in layers that are not as old have organisms that more resemble organisms that are alive today.
Authigenic preservation
Specialized mineralization around organic material which produces highly precise molds and casts
Trace Fossil
evidence of biologic activity that is preserved in the fossil record, but it not the organism itself. Examples include footprints and burrows. Ichnology is the study of trace fossils.
stratagraphic
correlation
Matching disconnected rock strata over large distances.
lithographic correlation
type of stratigraphic correlation which the physical characteristics of rocks are used to correlate.
depositional environment
interpretation of the rock record which describes the cause of sedimentation (i.e. ancient beach, river, swamp, etc.).
Chronostratigraphic
correlation
A type of stratigraphic correlation which is based on similar ages.
biostratigraphic correlation
A type of stratigraphic correlation in which fossils are used to match different rock layers.
Antropocence
A newly-proposed time segment (an epoch) that would be representative of time since humans have changed (and left evidence behind within) the geologic record.
Stress
the force exerted per unit area
Strain
physical change that results in response to that force
Tension stress
apart
Divergent
stretching and thinning
Compressional Stress
together
convergent
shorting and thickening
Shear Stress
Sliding side to side Transform
Tearing
Deformation
When rocks are stressed, the resulting strain can be elastic, ductile, or brittle
Elastic Deformation
strain that is reversible after a stress is released. For example, when you stretch a rubber band, it elastically returns to its original shape after you release it.
Ductile Deformation
A bending, squishing, or stretching style of deformation where an object changes shape smoothly.
Yield Point
An amount of strain where the substance has a maximum amount of elastic deformation and switches to ductile deformation.
axial fold
Dividing two-dimensional line between the two sides of a fold.
monocline
A one-sided fold-like structure in which layers of rock warp upwards or down- wards.
Riecter Scale
A magnitude scale using the amplitude of shaking via a seismograph.
Modified Mercalli Scale
A qualitative earthquake scale, from I-XII, of the degree of shaking in an earth- quake.
oxygen
O
47% of crust
Silicon
Si
28% of crust
Aluminum
Al
8% of crust
Iron
Fe
5% of crust
Calcium
Ca
4% of crust
Sodium
Na
3% of crust
Potassium
K 3%
Magnesium
Mg
2%
Valence shell
outermost electron shell
octet rule
A rule that says the outer valence shell of electrons is complete when it contains 8 electrons.
innermost shell
maximum of two electrons
anions
A negatively-charged ion. In geology, this commonly includes elements and molecules like SiO4-4, S-2, SO4-4, and O-2.
cations
A positively-charged ion. In geology, this commonly includes ions of the elements Ca+2, Na+1, K+1, Fe+2,+3, Al+3, and Mg+2.
minerals
form when atoms bond together in a crystalline arrangement
minerals ( Precipitation from aqueous solution )
minerals can be disovled in water over a period of time, water that is hard with minerals can create minerals again
minerals (Crystallization from Magma )
when lava begins to cool it can form crystals of minerals
A specific chemical composition that forms different minerals and different temperatures and pressures. Quartz has several different polymorphs, including co- esite, tridimite, and stishovite.
Mafic
a volcanic rock with lower silica composition, or the minerals that make up
those rocks, namely olivine, pyroxene, amphibole, and biotite. Mafic rocks are darker in color and contain more minerals that are dark in color, but can contain some plagioclase feldspar. Primary mafic rocks are basalt (extrusive) and gabbro (intrusive).
olivine family
Silicate
pyroxene
any of a large class of rock-forming silicate minerals, generally containing calcium, magnesium, and iron and typically occurring as prismatic crystals.
Amphibole Family
an be many colors, but the common form, hornblende, is dark brown to black. Has two cleavages at 54° and 126°. Crystals are typically elongated needles or diamond shapes. Common in many igneous rocks and some metamorphic rocks. Structure is a double chain of silica tetrahedra.
Sheet Silicates
form when each tetrahedron shares three of its oxygen atoms with other tetrahedra
Framework Silicates
- Includes Quartz and Feldspars
- Structure- weather resistant
Non-Silicate Minerals
a mineral that does not contain compounds of silicon and oxygen
Carbonates
Minerals that contain the elements carbon, oxygen, and one or more other metallic elements
Oxides
compounds that contain oxygen and an element other than silicon
Halides
Minerals that contain a halogen ion plus one or more other elements
Sulfides
compounds that consist of one or more elements combined with sulfur
Phosphates
Phosphorous-based nutrients commonly found in fertilizers and pesticides.
Native Element Minerals
a mineral consisting of only one element
ways to identify minerals
Color, luster, streak, cleavage and fracture, hardness, density, special properties
specific gravity
Related to density; the ratio of the weight of a mineral vs. the weight of an equal volume of water.
Phanertic
Large, easy-to-see crystals within an igneous rock. This is common in intrusive rocks.
Aphantic
Small, microscopic, hard-to-see crystals (i.e. no visible crystals) within an igneous rock. This is common in extrusive rocks.
Porphyritic
igneous rock with two distinctive crystal sizes. This is common in intrusive or extrusive rocks.
phenocryst
A large crystal within an igneous rock. These can be seen within phaneritic and porphyritic rocks.
Pegmatite
rock (or texture within a rock) with unusually-large crystals, minerals with rare trace element concentrations, and/or unusual minerals, typically forming in veins as the last dredges of magma crystallize.
sills
A type of dike that is parallel to bedding planes within the bedrock.
Lacoliths
arge igneous intrusion that is wedged between sedimentary layers, bulging upwards. Called a lopolith if bulging downward.
batholiths
Used to describe a large mass or chain of many plutons and intrusive rocks.
Bowen’s Reaction Series
describes the temperature at which minerals crystallize when cooled, or melt when heated. The low end of the temperature scale where all minerals crystallize into solid rock, is approximately 700°C (1292°F). The upper end of the range where all minerals exist in a molten state, is approximately 1,250°C (2,282°F).
four groups of igneous rock
ultramafic, mafic, intermediate, and felsic
flux melting
The process in which volatiles enter the mantle wedge, and the volatiles lower the melting temperature, causing volcanism
assimilation
Bedrock around the magma chamber being incorporated into the magma, some- times changing the composition of the magma
fractionation
The process of a magma changing from mafic to felsic via cooling. As the magma cools, higher temperature, mafic minerals crystalize, and a more felsic magma is left.
chemosynthesis
A biologic process of gaining energy from chemicals from within the Earth, similar to using the energy of the sun in photosynthesis.
Stratovolcano
The most common volcano. Known for its layers of lava flows and cinder. Built up by violent eruptions that leave the tephra followed by calm eruptions that leave lava flows. They build tall and steep volcanoes.
magma chamber, lithosphere, conduit or shoot, diapar feeder tube, tephra or ash layer
A parasitic cone
a volcanic cone that forms on the flank of a larger volcano
shield volcanoes
Gently sloping mountains formed by thin, runny lava. As the lava spreads and cools, it forms a shield shape like a gladiator’s shield.
fissures
deep grooves
stratovolcano
Volcano with steep sides, made of a composite of many types of eruption styles, from low viscosity mafic magma, higher viscosity felsic lava, but most commonly, intermediate andesite lava.
lava domes
bulbous mass of congealed lava; associated with explosive eruptions
Calderas
a huge bowl-shaped depression formed when an empty magma chamber col- lapses after a volcanic eruption
cinder cone
A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano’s opening
flood basalts
Rare very low viscosity eruption that covers vast areas. None have been observed in human history.
carbonatite
An igneous rock consisting of 50% or more carbonate minerals. They are usually associated with rift-related tectonic zones.
pyroclastic flows
scalding avalanche of ash and hot, toxic expanding gas, traveling very fast down the flank of a volcano
Lahar
An avalanche of volcanic water and mud down the slopes of a volcano
low silica magma
typically forms hot, low viscosity lava that easily flows from vents. The lava is nonexplosive since it allows gases to easily escape while it’s moving.
high silica magma
Aka felsic magma from granite. Creates explosive, violent eruptions with “pyro- clastic materials”.
compositional layers of the
earth
crust, mantle, core
mechanical lay- ers of the earth
lithosphere- crust and upper mantle. asthenosphere-upper mantle and below the lithosphere.
dehydration
melting
Water rich serpentine in the oceanic crust dehydrates as it heats up while it subducts into the mantle.
The water melts the olivines, pyroxenes, and feldspar to create andesitic lava 60% silica.
decompression melting
melting due to a drop in confining pressure that occurs as rock rises
