Unit 4 Flashcards
Core
Dense mass of nickel, iron, and radioactive elements that release massive amounts of heat
Mantle
bulk of Earth’s interior; three layers
Magma
(molten rock) layer that slowly circulates due to heat from core
Asthenosphere
semi-molten, flexible outer layer of mantle, beneath the lithosphere
Lithosphere
thin, brittle layer of rock floating on top of mantle (broken up into tectonic plates)
Crust
very outer layer of the lithosphere, Earth’s surface
Tectonic plates
Lithosphere floats atop the asthenosphere and can move and break into large pieces
Convergent
Two plates pushed toward each other
One of the plates will be pushed deep into the mantle
Subduction occurs → results in uplifting plates to form large mountain chains
Divergent
Two plates moving away from each other
Causes a gap that can be filled with magma → cools to form a new crust
Transform fault
Two plates slide from side to side relative to each other
Mountains formed by….
Mountains formed by magma from earth’s interiors
Magma heated by earth’s core rises towards lithosphere
Rising magma forces oceanic plates apart
Creates . . .
mid ocean ridges, volcanoes, spreading zones or “seafloor spreading”
Oceanic-Oceanic
one plate subducts underneath other
Forces magma up to lithosphere surface, forming mid ocean volcanoes
Island arcs
Off-shore trench
Oceanic-Continental
dense oceanic plate subducts beneath cont. Plate & melts back into magma
Forces magma up to lithosphere surface
Coastal Mountains (Andes), Volcanoes on land, trenches, tsunamis
Continental-Continental
surface crust from both plates “buckles” upward (mountains)
Ex: Himalayas
Ring of Fire
pattern of volcanoes & earthquake zones all around pacific plate
Offshore island arcs (Japan)
Transform faults
likely location of earthquakes
Hotspots
areas of especially hot magma rising up to lithosphere
Mid-ocean Islands (Iceland, Hawaii)
Humus
main organic part of soil (broken down biomass like leaves, dead animals, waste, etc.)
Weathering
Breakdown of rocks into smaller pieces
Physical (wind, rain, freezing/thawing of ice)
Biological (roots of trees crack rocks)
Chemical (acid rain, acids from moss/lichen)
Weathering of rocks = soil formation
Broken into smaller and smaller pieces
Carried away and deposited by erosion
Erosion
Transport of weathered rock fragments by wind and rain
Carried to new location and deposited (deposition)
Climate on soil formation
warmer = faster breakdown of org. matter;
more precip. = more weathering, erosion + deposition
Weathering of parent material(soil pH, nutrient content) produces
smaller, and smaller fragments that make up geological/inorganic part of soil
Sand, silt, clay
Minerals
O horizon
(organic horizon)
Uppermost horizon
Mostly made up of organic material including waste from organisms, bodies of decomposing organisms, live organisms
Dark crumbly material from the decomposition of organic material forms humus
Humus is rich in organic matter
A horizon
Made up of weathered rock and some organic material that has traveled down from the O layer
Called “topsoil”
Zone of leaching
Important role in plant growth
E horizon
(could occur beneath O or A horizon)
Leached of clay, minerals, and organic matter, leaving a concentration of sand and silt particles of quartz or other resistant materials – missing in some soils but often found in older soils and forest soils.
B horizon
Receives all minerals that are leached out of A horizon as well as organic materials that are washed down from the topsoil above
Zone of illuviation
Movement of dissolved material from higher soil layers to lower soil layers due to the downward movement of water (caused by gravity)
C horizon
Bottommost layer of soil
Composed of larger pieces of rock that have not undergone as much weathering
R horizon
“Bedrock”
Lies below all other layers of soil
Loss of Topsoil
tilling (turning soil for agriculture) + loss of
vegetation disturb soil and make it more easily eroded by wind and rain
Loss of top soil dries out soil, removes nutrients + soil organisms that recycle nutrients
Compaction
compression of soil by machines (tractors, bulldozers, etc.), grazing livestock, and humans reduces ability to hold moisture
Dry soil erodes more easily
Dry soil supports less plant growth, less root structure, leading to more erosion
Soil Degradation
The loss of the ability of soil to support plant growth
Nutrient Depletion
epeatedly growing crops on the same soil removes key nutrients (N, P, K, Na, Mg) over time
Reduces ability to grow future crops
Monoculture