50 terms

Weathering & Erosion 1

STUDY
PLAY
external processes
weathering, mass wasting, and erosion. Processes that happen on earths surface.
internal processes
derive energy from earths interior. mean while, opposing external processes are continually breaking apart rock and moving debris.
weathering
the physical breakdown and chemical alteration of rocks at/near earths surface.
mass wasting
the downward movement of rock, regolith, and soil under direct influence of gravity
erosion
the physical removal of material by mobile agents(wind, water, ice ).
mechanical weathering
when physical forces break rock into smaller and smaller pieces without changing the mineral composition
chemical weathering
a chemical transformation of rock into one or more new compounds (change in rocks composition)
three physical processes for breaking rock
frost wedging, expansion from unloading, biological activity
frost wedging
the process of water freezing and thawing inside a rock, expanding cracks
talus slopes
large piles forming at the base of steep rocky cliffs
sheeting
process by which slabs begin to break loose from an exfoliation dome
exfoliation domes
rocks that sheeting occurs on (commonly made of granite)
spheroidal weathering
giving a weathered rock a rounded or spherical shape
differential weathering
when masses of rock do NOT weather uniformly
interface
a common boundary where different parts of a system interact.
regolith
layer of rock and mineral fragments produced by weathering
soil
a combination of mineral and organic matter, water, and air
humus
decayed remains of animal and plant life
soil water
water containing many nutrients, far from "pure" water.
parent material
source of weathered mineral matter from which soils develop.
residual soil
soil that forms upon bedrock
transported soil
soil that forms on unconsolidated sediment
slope orientation
the direction a given slope is facing
horizons
zones/layers divided into the depths of earths soil
soil profile
displays differentiating horizons
eluviation
the washing out of fine soil components
leaching
when water dissolves minerals carrying them down into deeper zones
solum
"true soil" made up of all horizons
immature soils
soils that lack horizons
soil taxonomy
system used for classifying soil types (12 basic soil orders)
rock cycle
recycling of earth's rocks
secondary enrichment
when important mineral deposits are created by concentrating minor amounts of metals that are scattered through unweathered rock into economically valuable concentrations
trigger
event that initiates downward movement
angle of repose
stable angle that particles assume at rest
fall
movement of detached individual pieces of rock
slides
when material remains fairly coherent and moves along a well defined surface
slump
descending material moves in masses along a curves surface of rupture
flow
when material moves downslope as a fluid
rock avalanche
when rock and debris hurtle downslope at speeds exceeding 125 mph
creep
a type of mass wasting that involves the gradual downhill movement of soil and regolith
lahars
debris flows mainly composed of volcanic materials on the flanks of volcanos.
earth-flow
form on hillsides in humid areas during heavy precipitation
liquefaction
earth flows in association with earth quakes
slow movements
the subtle forms of mass wasting: creep, solifluction, etc.
solifluction
when soil is saturated with water, the soggy mass may flow down slope at a rate of a few millimeters/centimeters per day/year (common over permafrost)
permafrost
permanently frozen ground that occurs on earths tundra
debris flow (mudflow)
mixture of soil, regolith, and water flowing down, following pre-made paths
rockslide
bedrock breaks and falls down
soil texture
proportion of different particle sizes in soil (clay, silt, sand)
peds
clumps of soil called: platy, prismatic, blocky, spheroidal