Earth's Changing Surface - Rock-it Science (no photos)

weathering

weathering

breakdown of rocks at the Earth's surface, by the action of rainwater, extremes of temperature, and biological activity

erosion

the action of wind, water, and glacial ice that transports soil, rock, or dissolved material from one location to another

deposition

the process of laying down eroded material in a new location

physical weathering

breaking down rocks into smaller pieces without changing their composition through processes like freezing and thawing or plants growing into and expanding cracks in rock

chemical weathering

the process of changing the composition of rocks and minerals by exposure to water and the atmosphere

chemical composition

the types, quantities, and arrangements of elements that make up a substance.

humus

dark organic matter that forms in soil when dead plant and animal matter breaks down

soil

weathered rock, mineral material, water, air, and organic matter from the remains of organisms that can support the growth of vegetation

sediment

small, solid pieces of material that come from rocks or living things

soil formation

weathering process fractures and breaks down rock; plants, bacteria and burrowing organisms break down rock; organic material from plants and other organisms begins to build up in upper layer; upper layer becomes thicker and nutrient-rich

V-shaped valleys

channel type formed in the upper course of a river where discharge is lower

vertical erosion

downward removal of material typical of the upper course of a river

lateral erosion

side to side removal of material typical of the middle and lower course of a river

waterfall

formed when a lower layer of less resistant rock erodes more quickly, undercutting a more resistant upper layer rock, creating an overhang

gorge

created as processes forming a waterfall migrate upstream

rapids

form where the water is relatively shallow and the stream gradient steepens abruptly or from flowing over thin layers of alternating hard and soft rock

upper stream

part of stream characterized by interlocking spurs (ridges that extend alternately), and by erosion

middle and lower stream

part of stream characterized by both erosion and deposition

stream load

material transported by the river

forms of river transport

traction (e.g. boulders & pebbles dragged along stream bed), saltation (e.g. sand bouncing along stream bed), suspension (e.g. clay and silt that are light enough to float in the moving water), solution (minerals/chemicals dissolved in water)

stream bed

bottom of the channel

meander

bend in a river; erosion occurs on the outside of the curve where the water flow is fastest; deposition occurs on the inside of the curve where water flow is slowest

oxbow lake

form when a meander is cut off; characteristic of the lower course of a river

flood plain

formed by deposition during flooding beyond the banks of a river; course sediment is deposited closest to a river forming a levee and finer sediment is carried farther away from the river banks

delta

forms at the mouth of a river when it meets a lake or the sea; results when stream velocity declines abruptly and the sediment load is deposited in a fan shape; these "outies" form when sea levels aren't rising

estuary

partly enclosed coastal body of water in which river water is mixed with seawater; these "innies" form at the mouth of a river when rising seas flood river valleys

channel

area that contains flowing water confined by banks; may be straight, meandering, braided

sinuosity

a measure of how curvy a stream is calculated by dividing curvy length along the stream channel, by the straight line distance--the higher it is, the more curvy a stream is

relief

difference in elevation calculated by subtracting the lowest elevation from the highest elevation

velocity

the speed of the water; determined by floating an object between two points on the river and recording the time it takes, then dividing distance traveled by the time

gradient

measure of the slope of the river over a particular distance; calculated by dividing the relief by the curvy distance (rise/run)

the measure of how much water flows past a given location on the stream per second; calculated by multiplying velocity with the cross-sectional area

discharge

headwaters

the source of a stream or river

tributary

a river or stream flowing into a larger river or lake

watershed

an area of land that contains a common set of streams and rivers that all drain into a single larger body of water, such as a larger river, a lake or an ocean; also called drainage basin

drainage divide

a highland or ridge that separates one watershed from another

Cedar River Lake Washington Watershed

Northstar is located in this

stream energy

the potential energy created by the difference in elevation between the headwaters and base of a stream

overland flow

water that moves across the Earth's surface from precipitation or snowmelt that does absorb into the soil

ephemeral stream

seasonal stream fed mainly by precipitation and overland flow

perennial stream

flow year round and fed by mainly by groundwater flow

permeable

porous material that allows water to easily pass through it; soil and rock with this characteristic absorbs water easily, minimizing the affects of flooding

impervious

unable to absorb water; soil, rock and urbanized areas with this characteristic are prone to flash flooding

channelize

to create an artificial channel through which a stream or river flows using engineered structures to straighten a stream and eliminate it's natural tendency to meander

wetlands

slow, absorb, store, and filter water