APES unit 4 exam

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 layer of the lithosphere, Earth’s surface

Divergent Plate Boundary

plates move away from each other

rising magma plume from mantle forces plates apart

forms: mid-oceanic ridges, seafloor spreading, and rift valleys

Convergent Plate Boundary

Plates move towards each other

leads to subduction (one plate being forced beneath another)

forms: mountains, island arcs, and volcanoes

Transform Fault Plate Boundary

Plates slide sideways past each other

forms: faults

Ring of Fire

pattern of volcanoes & earthquake zones all around pacific plate

Hotspots

areas of especially hot magma rising up to lithosphere

Soil

Mix of geologic (rock) and organic (living) components

Sand, silt, clay, humus, nutrients, water and air, living organisms

Weathering

Breakdown of rocks into smaller pieces

physical, biological, chemical

Erosion

Transport of weathered rock fragments by wind and rain

carried to new location and deposited

Soil Horizons: O-Horizon

layer of organic matter (plant roots, dead leaves, animal waste) on top of soil

provides nutrients and limits H20 loss to evaporation

Soil Horizons: A- Horizon

topsoil; layer of humus (decomposed organic matter) and minerals from parent material

A-Horizon has most biological activity breaking down organic matter to release nutrients

Soil Horizons: B-Horizon

subsoil; lighter layer below topsoil, mostly made of mineral w/ little to no org. matter

contains some nutrients

Soil Horizons: C-Horizon

least weathered soil that is closest to the parent material

Soil Degradation

The loss of the ability of soil to support plant growth

Loss of topsoil

tilting (turning soil for agriculture) + loss of vegetation disturb soil and make it more earily eroded by wind and rain

loss of top soil dries out soil, removes nutrients + soil organisms that recycle nutrients

compaction

compression fo soil by machines, grazing livestock, and humans reduce ability to hold moisture