Intro to Landform Flashcards
Structure of Earth
1) crust
2) mantle
3) core
Crust
1) ~4 miles thick w. 2 types - continental, oceanic
2) ocean = thinner BUT denser rocks
3) density of crust increases w. depth
4) significant change in mineral comp. at base of crust (mohorovicic discontinuity aka moho)
Mantle
1) Upper mantle = thin + rigid, called lithosphere
2) Asthenosphere = beneath lithosphere = hot rocks that become plastic like
3) low mantle = very hot rocks BUT rigid bc of pressure
Core
1) warmth = release of energy from decay of radioactive elements
2) outer core = liquid
3) inner core = dense solid
Igneous Rocks
1) formed by cooling + solidification of molten rock (magma)
2) Examples = granite, diorite, gabbro
Sedimentary Rock
1) sedimentary deposits build up –> compacted + consolidate into sedimentary rock
2) Distinct layers - strata
Metamorphic Rocks
1) rock physically/chemically altered by heat, pressure, chemically active fluids
2) associated w. lithosphere
3) types of metamorphism: contact (contact w. magma), regional (deep within crust exposed to heat/pressure), hydrothermal (fluids circulate thru cracks in rock)
Foliated vs Nonfoliated (metamorphic)
Foliated - layered/banded appearance bc minerals arranged in parallel layers
Non-foliated - plan, grainy texture, no layers
Clastic, Chemical, Organic Sedimentary
1) Clastic - formed from layers of debris, moved by water/wind (shale, sandstone)
2) Chemical - formed from minerals preciping out of solution (limestone from CaCO3)
3) Organic = formed from remains of organisms (coal)
Plutonic vs Volcanic (Igneous)
Plutonic/Intrusive = Form from magma cooling below surface (granite)
2) Volcanic/extrusive = form from cooling of lava ON surface (obsedian)
Internal Process
1) Originates from WITHIN Earth
2) result in crustal movements via folding, faulting, volcanic activity
3) Building up –> Increase relief features on earth
External Process
1) Operate at base of atmosphere + get energy from ABOVE lithosphere
2) Wearing down –> weathering, erosion
Relationship btwn internal + external
1) Internal BUILDS UP
2) External BREAKS DOWN
Uniformatirianism
1) present to key is past
2) Topography today shaped by same processes of the past + same in future
Catastrophism
1) Older idea than uniformitarianism
2) Major features produced by sudden upheavals + catastrophes
Continental Drift
1) Wegener postulated existence of Pangaea –> broke apart + moved to form present day continents
Evidence for Continental drift
1) close affinities of geologic features on both sides of Atlantic
2) Rock records on both sides of Atlantic would be continuous if ocean didn’t separate it
3) Africa + South America fit like a jigsaw puzzle
4) Fossils of dinosaurs + reptiles (Mesosaurus) found on both sides of southern Atlantic BUT nowhere else
Plate Tectonics Evidence
1) Using depth soundings –> created ocean floor topography
2) revealed chains of volcanoes (seamounts) + bands/ridges corresponded w. earthquakes
3) seafloor spreading + subduction
Seafloor spreadin
Midocean ridges formed by magma rising up from mantles –> volcanic eruptions create new basaltic ocean floor –> spreads away from ridge
FORMS new seafloor
Subduction
Ocean trenches –> ocean basin goes back into asthenosphere (into mantle)
seafloor DESTROYED
relationship btwn seafloor spreading + subduction
amount of new seafloor created in midocean ridges = amount lost in trenches
Paleomagnetism = proof of seafloor spreading
rock containing iron –> magnetized by magnetic field –> contains record of Earth’s polarity at time rock solidified
found bands of same polarity rocks on either side of midocean ridge
Ocean Floor Cores
Showed sediment thickness + age of fossils increased as got further from ridges –> proof that sediments farthest from ridge oldest
like a conveyer belt
Plate Tectonic Theory
1) Lithosphere has many rigid plates floating on plastic-like asthenosphere
2) Plates moved by convection in Earth’s mantle –> “pulled” by subduction of cold denser ocean lithosphere into asthenosphere
Mafic vs Felsic Igneous
Mafic - darker, heavier (basalt)
Felsic - lighter in color + density
Coarse vs fine igneous
Coase grain = to get large grains, you need time, pressure –> INSIDE magma chamber
fine grain = cools quickly outside so lava or volcanic eruption
Types of Igneous
1) Mafic or Felsic
2) Fine or coarse
3) Plutonic vs volcanic
Types of sedimentary
Clastic, Organic, Chemical
Types of metamorphic
nonfoliated, foliated
