weathering, erosion, deposition, and landscapes Flashcards
pysical weathering
the breakdown of rock without changing its chemical composition
frost action
when water freezes its expands, so when water freezes and a crack in a rock gets bigger, this is how pot holes form.
biological action
animals and plantroots break rock apart
abrasion
when sediments in a river bump into each other causing sediments to be round smooth
chemical weathering
the breakdown of rock while changing the chemical composition
oxidation
when iron minerals in a rock interact with the oxygen in the air it often causes rust
hydration
when minerals in a rock interact with the hydrosphere sometimes mineral can dissolve forming caves, caverns, or sink holes
mineral composition
harder minerals weather slower than softer minerals
particle size
the smaller the particles the faster they weather
climate
temperature: warmer temperatures cause a faster weathering rate.
chemical weathering
occurs more in warm, humid climates
A horizon
topsoil-high organic content and weathered bedrock
B horizon
-partially weathered bedrock with some organic material
C horizon
partially/slightly weathered rock
bedrock
parent material-the solid rock under the soil
the two components of soil
weathered bedrock and organic material (humus)
the difference between transported soil and residual soil
residual soil forms from the rocks below
transported soil was brought throughout the area by an agent of erosion
erosion
the removal of sediment
the four natural agents of erosion are:
water, glaciers, wind, gravity
gravity causes
mass movements (pulling rocks and sediments downhill)
examples of mass movements include:
landslides, soil creep, mud flows and mudslides, rock falls, debris falls, avalanches
rocks eroded by gravity appear
jagged and broken
deflation occurs when
wind carries away loose sediments and lowers the earth’s surface (this is a problem on farmland)
sandblasting
occurs when winds blow sand or silt against other rocks causing the surface of the rock to appear pitted.
as a glacier moves over land…
loose rocks and sediments freeze within the ice.
rocks within a glacier help the glacier to scratch and carve out the land below producing …
glacial grooves and parrallel scratches on the rocks called striations.
Glacial grooves show…
the direction that the glacier moved.
glacial rocks appear
sub-rounded (boat shaped) and or scratched.
because waves strike the shore at an angle, the water near shore is pushed in one direction along the shore causing…
longshore current
streams as agents of erosion carry sediments
In solution (suspension) = floating. by rolling, sliding, or bouncing along the bottom. These sediments appear rounded.
youthful swift flowing streams
begin in higher elevations, narrow channels, are fairly straight. Waterfalls and rapids are common.
mature streams begin to
erode outwards and become wider, current decreases, and curves in the river called meanders form.
flood plain
where sediments are deposited during a flood
old age
wide, slow moving river with more deposition than erosion, lots of meanders and oxbow lakes.
oxbow lake
a cutoff meanderer forms a lake
cutbank
when the bank of the stream errodes at a meander
sandbar
when deposition occurs along the inside bank of the meander
discharge
the volume (amount of water) the stream carries over time.
gradient
the slope of the land (how steep or flat the land is)
stream channel shape
wide, flat streams have slow moving water whereas narrow streams have fast moving water.
deposition
leaving behind of sediments
density
sediments with greater density are deposited first
size and change in velocity
as velocity decreases, larger sediments are deposited first.
shape of sediment
round sediments are deposited before flat ones
horizontal sorting
due to changes in gradient, discharge, velocity, or a combination of these
delta
occurs when a stream enters a quiet body of water
delta has fingerlake deposits of…
fresh, new sediment that has been transported down the stream.
vertical sorting
within the river or at the mouth of the river– the sediments deposit vertically due to changes in gradient, discharge, velocity, or a combination of these
sand dune
erosion on windward side (windy) and deposition on leeward (calm) side–sand dune is constantly migrating (moving) (think snow drifts)
tallus
a pile of rock debris due to rock falls
as a glacier recedes
it randomly deposits the rocks that were frozen in the ice (unsorted)
glaciers bring/deposit…
transported soils.
the way that glaciers deposit the sediments creates a
unique landscape which we will discuss later in the unit.
barrier island
small islands that form above the high tide water line due to the long shore current.
example of a barrier island
Outer Banks of North Carolina
Galveston, Texas
plain
low elevation, sedimentary rocks
plateau
medium elevation, sedimentary rocks
mountains
high elevation, metamorphic rocks
Rivers
carve V-shaped valleys
Glaciers
carve U-shaped valleys
humid climates create
rounded hills
watershed is
all land that drains to a specific location like a river or lake
which watershed do you live in?
Genesee River water shed
Why is important to protect our watershed
anything we do on land effects our streams and our lakes.
dendritic
flat gentle sloping areas (like our area)
trellis
areas of foldfol mountains
radial
areas of domes such as a volcanoe
annular
mountain regions
