APES Unit 1

convergent boundaries

result in creation of mountains, island arcs, earthquakes, and volcanoes

divergent boundaries

result in seafloor spreading, rift valleys, volcanoes and earthquakes

transform boundaries

result in earthquakes

core

center, composed of mostly iron, molten

mantle

thick solid zone surrounding core (second layer), most of earth mass

crust

outside layer, thinnest, consists of the continental and oceanic crust, oxygen is most abundant

rock

one or more minerals bound together

monomineralic

one mineral, ex. limestone- calcite (CaCO3), quartzite- quartz (SIO2)

Polymineralic

several minerals, ex. granite- quartz, feldspar, mica etc.

igneous

forms by molten material, form bulk of earths crust, ex. granite, obsidian, basalt, scoria

sedimentary

form by deposition under water, ex. shale, siltstone, sandstone

metamorphic

rock changed from another rock

physical weathering

thermal expansion, frost action, exfoliation

chemical weathering

carbonation, oxidation

5 agents of erosion

gravity, wind, ice, water and humans

infiltration

downward movement of water

porosity

percent of pore space (open space)

permeability

rate of infiltration

clay

fine particles, low permeability, naturally alkaline

silt

sedimentary consisting of particles between size of clay and sand, easily transported by water

sand

coarser than silt, high permeability, well drained

loam

equal mixture of clay, sand, silt and humus. rich in nutrients- ideal agricultural soil, holds water but not waterlogged

soil degradation

natural or human induced process that decreases the ability of land to support crops or livestock animals

splash erosion

impact of falling raindrops breaks up structure of topsoil

sheet erosion

without infiltration, water runs off and carries more particles with it

Rill- Gully Erosion

sheet erosion carves gullies in soil which carry water and soil particles

deforestation

accelerates erosion- temporary or permanent removal of large expanses of forest for agriculture, settlements or other uses

overcultivation

accelerates erosion- plow to control weeds and increase aeration- leaves no plant residue + significant soil loss can occur

overgrazing

accelerates erosion- when animals exceeds to carrying capacity for the particular rangeland

sedimentation

particles washed into rivers by erosion settle and disrupt stream and lake systems

aquifer depletion

groundwater suplies are diminished because water runs off land instead of infiltrating into the soil

desertification

process where erosion progressed to a point where the ecology and production classify a once fertile area as a desert

no/ low till farming

farming without plowing the land, avoids exposing the soil to direct sun, wind and water. requires switch from shallow rooted anual plants that require annual tillage to perennial deep rooted plants that dont need tillage

conservation tillage

using specialized tillers and planting machines that drill seeds directly through crop residues into undisturbed topsoil

strip cropping

planting alternating strips of a row crop (corn) and another crop that completley covers the soil (cover crop- alfalfa + clover)

contour farming

plowing across the slope of a hill rather than up and down. reduces erosion by slowing runoff and preventing water from gaining momentum as it flows down a slow increasing erosion

terracing

converting a hilly slope to flat terraces that follow the contours of the slope

shelterbelts/ windbreaks

rows of shrubs or trees that are planted next to or around fields to slow down the winds that could blow topsoil off the land

agro foresty/ alley cropping

crops and trees are grown together

pollyculture

different plants maturing at different times are planted together

rotational grazing

range managment where number and duration of grazing animals in controlled

crop rotation

corn- soy beans- oats- alfalfa- corn symbiotic relationship