Geology II Flashcards

Terms Definitions
calcareous sponges
An aggregate of Minerals
any planar arrangement of mineral grains or structural features within a rock
What are steep-sided, symmetrical volcanic peaks built of alternating layers of pyroclastic debris capped by high-viscosity andesitic to rhyolitic lava flows that solidify to form protective caps?
General wave mitigation
Dunes (barrier islands)
Parallel (not perpendicular) streets
Elevated buildings
Wide beaches
Sea walls
The focus of an earthquake.
slab-pull, slab-push, mantle convection
Why plate tectonics?
Cinder-Cone Volcanoes
When volcanic vents discharge pyroclasts, the solid fragments build up and form cinder cones. Paricutin - cornfield in Mexico, erupted for 9 years - cone to 424 meters and lava flowers covered 25 km. Cierro Negro, Nicaragua, more than 20 times. Costa Rica. Nastiest, builds stone.
A very coarse-grained igneous rock. Crystals of up to tens of centimeters across.
Weather pattern that makes cool summers and mild winters, heavy rain. If no westerlies, extreme weather
tension at deeper level
can stretch rock
Earth is approx how old
convergent boundries are also called______ because they are sites where lithosphere is descending into the mantle
subduction zones
A narrow, sharp-crested ridge formed by the upturned edge of a steeply dipping bed of resistant rock.
Alfred Wegener
Who came up with Continental Drift?
ridge push force
Elevated mid-ocean ridge pushes lithosphere away.
Resistance to flow (water v. honey). The speed with which magmas/lavas move is affected by their viscosity.
Site at which material (solid, liquid, and gases) reach the surface of the planet from the interior. A hill or mountain that forms from the accumulation of matter that erupts at the surface. Always has a neck. Magma underneath usually for around 100 years. Upwelling magma travels up the pipe and erupts in the central vent or neck.
Secondary Factors of Atmospheric disturbance
Lake Effects
physiological, land/sea effects
hanging wall moves down relative to footwall; forms when rock units are pulled apart and lengthened; tension-divergent
St. Peter Sandstone
basal unit of Tippecanoe sequence
Mt. Everest is located on what Continent
Coal is the altered remains of ancient
accounts for about 20% of sedimentary rocks, consists of sand sized sediments, form in a variety of environments
Sed. Rocks that consist of discrete fragments and particles that are cemented and compacted together have this texture.  Includes all detrital rocks
A sensitive instrument used to measure the intensity of Earth's magnetic field at various points.
- the study of earths magnetic field in the past
what type of stress occurs at a convergent boundary?
Mt. Mazama
Crater Lake, Oregon, fills the caldera of which mountain that collapsed about 7600 years ago?
Heat rises and cold air sinks, expand and get less dense
Shield volcanoes
Broad, gently sloping cone. Mauna Lao, on Hawaii. Effusive volcanoes - mafic - travel far making it broad.
Atmospheric Circulation processes
1. Differential heating of the planet
2. Balance of angular momentum (coriolis effect)
shear at deeper levels
shearing is typically distributed across a wide zone; deform and flow as weak solids; shear zone
The most common cements
calcite, silica, and iron oxide
rocks that form from the highest grade of metamorphism
Surface wave
Seismic waves that travel along the outer layer of Earth.
Slab pull
A mechanism that contributes to plate motion in which cool, dense oceanic crust sinks into the mantle and "pulls" the trailing lithosphere along.
Transform fault
A major strike-slip fault that cuts through the lithosphere and accommodates motion between two plates.
Convergent boundary
A boundary in which plates move together, resulting in oceanic lithosphere being thrust beneath an overriding plate, eventually to be reabsorbed into the mantle. It can also involve the collision of two continental plates to create a mountain system.
Moho Boundary
- Area between the crust and the mantle which marks the sudden change in seismic wave velocity
- not the bottom of the plate (that is the Asthenosphere)
organic matter, air, rocks/minerals, water.
Soil is made up of...
Igneous Rocks
All rocks that were formed by the solidification of molten rock. Fire rocks. Source of material: Melting of rocks in hot, deep crust and upper mantle where the temperatures reach 700 degrees Celsius or more needed to melt most rocks (or could exceed that at an even higher temperature). Rock-forming process: crystallization (solidification of magma).
Volcanic Dome
Look as though lava had been squeezed out of vent like toothpaste, with very little spreading. Domes often plug vents, trapping gases. Pressure increase until an explosion occurs, blasting the dome into fragments. Explosive - felsic - very viscous - dome grows huge just before explosion and steam goes out - means volcano is imminent. Mt. St. Helens in 1980.
The sides of a fold where curvature is at a minimum are termed
sed. rocks that consist of minerals forming a pattern of interlocking crystalline structure
nonelastic or crystalline texture
Outer core
A layer beneath the mantle about 2270 kilometers thick, which has the properties of a liquid.
A remnant or outlier of a thrust sheet that was isolated by erosion.
Sea Floor Structures
- mid ocean ridge (under water mtn range)
- fracture zones (offset the ridges)
- abyssal plains (deep, flat plains)
- islands (underwater volcanos)
- trenches (deepest parts of ocean)
From Spain to Cuba
Where do the Northeast trade winds move?
Cold Summers
If huge volcano, ash can block the sun for 2, 3, or 4 days especially in the summer, dropping the temperature to 2 or 3 degrees. Examples: 1700s in South Pacific, 1960s in Alaska, 1995 in Phillippines, Iceland a few months ago.
Within the worlds sed. rocks, fossils...
Modified Mercalli Intensity Scale
A 12-point scale developed to evaluate earthquake intensity based on the amount of damage to various structures.
Partial Melting
- When only part of the rock melts to create magma
- most magma comes from different sources of rock which are partially melted, tend to be more felsic than the original rock it melted from
Differential thermal expansion of minerals creates stress in rocks
Desert. Heat makes things expand, cool makes things shrink. Expanding and shrinking over and over puts stress on the rock - two extreme stresses. Minerals in the rock therefore go in different directions - expanding an pushing each other and effecting each other. This weakens the rocks and makes them into powder.
describe how clast transport affects the size, shape and sorting of clasts
size: decreases with more distance from shore
shape: becomes more rounded with distance from source
sorting: becomes better sorted with distance from source
A crustal rock dated to 150 Ma is how old
150 Million
Breaking down into smaller pieces
More cracks = increase Surface Area = faster and more efficient chemical reactions because easier to extract elements and distribute them to different areas.
Sea floor is subducted and continents converge...because continental crust cannot sink...India colliding with Asia as well as the Himalaya Mountains
What occurs at a continent-continent convergent plate boundary? Why is there no subduction? Where are examples of these boundaries in the modern world?
pahoehoe is ropy-looking; aa is clinkery
How does pahoehoe lava differ from aa lava?
Three ways that foliation can occur
1. Rotation of platy and /or elongated mineral grains into a new orientation
2. recrystalization of minerals to form new grains growing in the direction of preferred orientation
3. Changing the shape of equidimensional grains into elongated shapes that are aligned in a preferred orientation
It decreases the pressure of gases dissolved in the magma, permitting them to expand
If the bulge grows steep enough it may collapse. Explain how this can trigger an explosive eruption?
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