GENERAL GEOLOGY Flashcards
The study of the Earth’s material, structure, and history from its past to the present.
GEOLOGY
Deals with the composition and the processes occurring on Earth
Physical Geology
It deals with the origin and evolution of Earth and life on the planet, and examines the history embedded in rocks and fossils.
Historical Geology
A concept formulated by James Ussher that believes the Earth was created in 4004 BC
CATASTROPHISM
Conceptualized by the Father of Modern Geology, James Hutton, that states physical, chemical, and biological laws that operate today, also operated in the geologic past.
UNIFORMITARIANISM
Proposed by James Hutton, is a concept that says rocks were formed by
emplacement and solidification of lava from volcanoes
Plutonism
Proposed by Abraham Werner, a concept that says rocks had settled out of a large ocean whose level gradually dropped over.
Neptunism
Similar to uniformitarianism, but events occur at different rates.
Actualism
Danish anatomist and geologist, and the Father of Stratigraphy.
Nicolas Steno
Younger strata lie on top of the older strata.
Law of Superposition
Beds were originally deposited nearly horizontally due to gravitational pull,
Law of Original Horizontality
Strata are deposited laterally until the sediment supply lasts or encounter any geologic barrier
Law of Lateral Continuity
According to Charles Lyell, structures that cut across strata are younger
Law of Cross-cutting Relationship -
According to Charles Lyell, rocks that have been included are relatively older than the host rock
Law of Inclusion
Igneous or metamorphic rock inclusions.
Xenoliths
Sedimentary rock inclusions.
Clasts
According to William Smith, ordering of strata by examining contained fossil
Law of Fossil Succession
Remains or traces of prehistoric life, were essential in the development of the geologic time scale.
Fossil
Events or strata are placed in their proper sequence or order without knowing their age in years
Relative dating
Procedure of calculating the absolute or approximate ages of rocks and minerals containing certain radioactive isotopes
Absolute dating
A chart that divides the vast 4.6-billion-year history of Earth into Eons, Eras, Periods, and epochs that utilize the absolute and relative ages of the rocks.
Geologic Time Scale
A dynamic mass of water that is continually on the move, evaporating from the oceans to the atmosphere, precipitating back to the land, and running back to the ocean.
*Covers 71% of the Earth’s surface, and has an average depth of about 3,800m or 12,500 ft.
HYDROSPHERE
Layers of gases that surround the planet Earth retained by the Earth’s gravity
ATMOSPHERE
A division of the Earth’s atmosphere, that extends from the mean sea level to about 100 km above sea level, where the mix of gases roughly constant
Homosphere
A division of the Earth’s atmosphere found above the Homosphere where the mixture of gases radically changes with altitude.
Heterosphere
The lowest and densest layer of the Earth’s atmosphere extends from the mean sea level up to an average of 10 km. above sea level, the tropopause contains roughly 80% of the mass of the Earth’s atmosphere and is where most of the weather and climate phenomena are confined.
TROPOSPHERE
Extends to approximately 9 km above sea level at the poles, and approximately about 17 km above sea level at the equator
TROPOSPHERE
Boundary between the Troposphere and the Stratosphere.
Tropopause
The second major layer in the atmosphere extends from the Tropopause up to about 50 km above sea level and contains the ozone layer.
STRATOSPHERE
Boundary between the Stratosphere and Mesosphere.
Stratopause
Part of the atmosphere that contains a relatively high concentration of ozone, which also protects the Earth from UV rays, but traps the rays that enter
Ozone Layer
Penetrates glass & deep into the skin, causing skin damage and aging.
UV-A
Dangerous between 10:00AM to 4:00PM, with its rays able to cause skin cancer, but can be easily blocked by glass & clothes
UV-B
Deadliest of the three UV rays, but mostly absorbed by the Earth’s atmosphere.
UV-C
The third layer of the Earth’s atmosphere extends from the Stratopause to about 85 km above sea level, with the temperature within this layer dropping with increasing altitude, having an average temperature of about -85°C.
MESOSPHERE
The boundary between the Mesosphere and Thermosphere
Mesopause
Also called night clouds, are tenuous cloud-like phenomena appearing in the Mesosphere.
Noctilucent clouds
The layer in the atmosphere that extends from the Mesopause to about 600 km above sea level, and is completely cloudless and water vapor-free. Auroras also occur within the Thermosphere.
THERMOSPHERE
A natural phenomenon that is the result of disturbances in the magnetosphere, caused by solar winds, and is found in high latitude regions.
Auroras
A dynamic comet-shaped region around the planet created by the interaction of solar wind with Earth’s magnetic field, that acts as a barrier of Earth from space weather.
Magnetosphere
The International Space Station (ISS) orbits within the ________________, between 350 and 420 km above sea level
Thermosphere
The outermost layer of the Earth’s atmosphere extends up to 10,000 km above sea level and contains most of the satellites orbiting the planet.
EXOSPHERE
The boundary between the Thermosphere and Exosphere
Exobase
border the Earth’s Atmosphere and the beginning of space
Karman line
Encompasses the solid Earth that extends from the surface to the center of the planet, about __________ deep.
GEOSPHERE
6,400 km
The process of transforming original pieces of matter into ordered, concentric layers that are separated by physical and chemical properties
Differentiation
The process of gradual accumulation of additional layers of material, causing a growth or increase in body mass
Accretion
Homogeneous Accretion (Ringwood, 1979) 2-step process:
Accretion of a homogenous or undifferentiated proto-Earth B. Subsequent differentiation into a metallic core and silicate mantle
Core and mantle material simultaneously formed, but accreted and differentiated at a separate time
Heterogeneous Accretion (Turkenia and Clark, 1969)
The Earth experienced a large-scale melting, that may have been due to continuous collisions of planetesimals the radioactive decay of short-lived nuclides, or the effects of the excess greenhouse gases, and formed one or more magma oceans during the late stage of its accretion
Magma Ocean Model
The outermost layer of the Earth by chemical composition
Crust
The boundary between Upper and Lower Crust.
Conrad Discontinuity
Continental crust average density of ____________
2.7 g/cm³
Generally granitic in composition, but dioritic and/or gabbroic in the lower portion
Generally granitic in composition, but dioritic and/or gabbroic in the lower portion
The continental crust is About ____ to ____ thick, sometimes reaching _____
30 to 80 km
100 km
The oldest continental rocks reach up to ___________________
4.28 Ga in Greenstone Belts
Oceanic crust average density of ____________
3.0 g/cm³
Generally basaltic in composition
oceanic crust
Oceanic crust is About ________ thick, the older or cooler it is, the thicker it is
3 to 10 km
The oldest oceanic crust is ______ along the Western Pacific Ocean and Eastern Atlantic Ocean
180 Ma
A solid, rocky shell that constitutes the great bulk of the Earth.
Mantle
The mantle is ___ by volume and ___ by mass
83%
62%
The mantle extends to a depth of________ deep.
2900 km
The uppermost part of the mantle is dominantly ___________
peridotite
The boundary between Crust and Mantle
Mohorovicic Discontinuity
Core Central mass that’s about ________ in radius, making up about ___ of the Earth’s volume
3,480 km
16%
the core is composed of an____________
iron-nickel alloy
the core with an average density of nearly _________ due to extreme pressure
11 g/cm
The boundary between Mantle and Core.
Gutenburg Discontinuity
The rigid outer physical layer consists of the entire crust and upper mantle, which ruptures due to stress, producing earthquakes, and breaking into large fragments called plates.
Lithosphere
Boundary between Lithosphere and Asthenosphere
Mohorovicic Discontinuity
Contact between the Lithosphere and the Asthenosphere where small in P-wave velocity.
Low Velocity Zone
Plastic is free-flowing enough not to rupture when subjected to stress, but has more rigid solids than the Low Velocity Zone, increasing the P-wave velocity.
Asthenosphere
The asthenosphere is dominantly composed of ___________________
Olivine, Pyroxene, and Garnet.
Contact between the Asthenosphere and the Mesosphere, where at this layer, Oliving transforms into Wadleysite, which transforms into Ringwoodite, and together, with Garnet, transforms into Perovskite and Periclase at the depth of 660 km
Transition Zone
Boundary between Asthenosphere and Mesosphere
Repiti Discontinuity
The lower mantle extends from 660 km to 2900 km in depth. Dominantly composed of Perovskite, Periclase, Magnesiowustite, Stishovite, Ilmenite, and Ferrite.
Mesosphere
Common site of anomalous seismic signals. Characterized by anomalously fast velocities that may have been caused by lithosphere subducted all the way down to the D” layer. It contains the Ultra-Low Velocity Zone (UVLZ) in the lowermost part
D” Layer
Found in the lowermost part of the D” Layer that causes a large decrease in P-Wave velocity, and may be related to the formation of deep mantle plumes within the lower mantle
Ultra-Low Velocity Zone
Boundary between Mesosphere and Outer Core.
Gutenburg discontinuity
A dramatic decrease in P-Wave velocity and absence of S-Wave due to the layer being liquid. The circulation of the molten iron causes geodynamo.
Outer Core
Outer Core is highly incompressible with a density of ___________
10-12 g/cm³
Outer Core is Dominantly composed of ______________
liquid iron and nickel alloy.
The production of most of Earth’s magnetic field.
Geodynamo
A solid inner core that is __________ in density, that has a rapid increase in P-Wave velocity and reoccurrence of S-Wave velocity.
13 g/cm³
It is seismically anisotropic, which makes seismic velocity travel faster in one direction compared to the rest due to the parallel alignment of iron-rich crystals.
Inner core
an Earth’s external structures are Typically located in the interior of the continents
Extensive, flat stable areas
an Earth’s external structures are Long, narrow features at the margins of continents
Uplifted regions
The average elevation of the continental features is about ___________
0.8 km.
Sites of tectonic convergence with uplifted mountain ranges.
Mountain belts
Includes the region surrounding the Pacific Ocean: the mountains of the western Americas and the island arcs in the eastern Pacific.
Circum-Pacific Belt
Found along the boundary of the Indian plate and Eurasian plate
Alps and the Himalayas
Found in the Eastern United States
Appalachians
where are the Appalachians found in?
Eastern United States
where are the Urals found in?
Russia
The interiors of the continents have been relatively stable or undisturbed for at least 600 million years.
Stable interior
