streams Flashcards
the initial driving force
evaporation and then condensation
sun
mountain range
a streams beginning
source
a streams end another body of water ocean lake River
mouth
landform at mouth that projects into another quiet body of water
Mississippi
Nile
delta
a River and all of its tributaries
River system
a stream that ends in the main River
tributary
the area of land drained by a River system
drainage basin
watersheds
all of the water that falls in a certain watershed will remain in the watershed
basins
ridges that separate watersheds
two major divides (continental) in the US
Appalachians and Rocky Mountains
divide
V-shaped
down-cutting
few tributaries
youthful- stage 1
floodplain develops
more tributaries
mature- stage 2
meandering channel, lots of tributaries
wide floodplain
oxbows and cut-offs
old stage- stage 3
channel and v-shaped valley floodplain point bar cut bank tributaries source mouth and delta meanders and oxbow lakes
parts of a River
water overflows banks and floods the floodplain
caused by heavy rainfall, snow melt
most pronounced in the spring
most erosion occurs during this
flooding
large material carried alon the bed or bottom of the stream
boulders, pebbles, and sand
bed loads
material that is held in suspension
clay and silts
suspend load
minerals that have been dissolved by the water
can’t be seen, must be tested chemically
dissolved load
the amount of water moving by a certain point of a stream
multiply the volume of a River by its velocity and you will get discharge
usually measured in cubic feet per second
speed depends mostly on a streams gradient
volume usually depends on amount of rainfall and drainage basin size
discharge
a period in which ice extends farther than normal
last one began about 1 million years ago
returned to normal about 12000 years ago
Ice ages
cool summers
little or no ice melts
period of cooling
what causes cooling
change in Suns energy
earths tilt, orbit
change in positions of continents
volcanos
leads to cooling of the polar regions
milankovitch cycle
changes CO2 content
less CO2
less global warming gases
reef building
limestone
form in mountains
rivers of ice
alpine valley
ice sheets
cover 100-1000 square miles
Greenland and Antarctica
continental glaciers
grinding of bedrock
Rock is carried by glacier and scratches bedrock
glacial grooves
abrasion
glacier grabs rocks and pulls them out of the ground
pucking
huge, flat areas
Great Plains
huge flat areas
glacial grooves
the Great Lakes
rebound terraces
continental- erosional
piles of unlayered sediment lateral medial end recessional terminal moraines
depositional features
layered
outwash
sediment deposited by the glacier till outwash drumlins eskers Kames kettle lakes moraine-dammed lakes
continental deposits
formed by waves weathering and eroding the shoreline
erosional
waves attack land
erosion
caused by storms off shore
waves
length of open water
larger this is the larger the waves
FETCH
deposit eroded material
sand and clay
weathering and erosion from waves
rocky shore
sand is pushed back from the deeper water
gulf coast of Florida
shells
storms cause beaches to erode
short wavelengths
winter
long wavelengths
sand pushed onto shore
beaches get rebuilt
summer
wavelength/ period (ft/sec)
wave speed
depth is 1/2 of wavelength
wave energy
form when wave feels bottom
breaker
wave is bent as it feels bottom
wave energy is concentrated on headlands
causes water and sand to move parallel to shore
wave refraction
land that protrudes into the ocean
headland
zigzag motion in surf zone
smash and backwash
movement of loose earth material down a slope
driving force is gravity
can happen quickly or slowly
Gravity is the driving force, but water is usually the trigger
mass movement
steep slope over- steepening due to humans overloading the top of the e slope deforestation or removal of vegetation weak material such as shale is not resistant to weathering and erosion
how slides occur
includes all precipitation that falls on land
moves downhill due to gravity
water comes together and forms streams and rivers
an agent of weather and erosion
running water
falls through the air
fall
tumbling down the hill
flow
slides down the hill Material can be divided into Rock mud debris
slide
arid regions characterized by less than 25 cm of rain per year
often hot, but dry, cold places like Antarctica qualify as these too
deserts
what does warm air do at the equator
rises
when does the dry air sink
when is reaches 30°
caused by mountains
rain shadow effect
rocks shaped by wind
desert varnish
desert pavement
ventifacts
a hill made out of sand created by a series of winds
form in different shapes and sizes
sand dunes
crescent shaped with horns of the dune pointing downwind
barchan
a giant ripple like sand dune formed at a right angle to the direction of the prevailing winds
transverse dunes
depositional features made of bills of sand that are stabilized by vegetation at each end
blowout
parabolic dunes
depositional feature formed when wind is parallel to dune direction
longitudinal dunes
resembles a star because the wind direction is variable
star dunes
wind blown sediments
deposits can be very thick
loess
water that flows underground
water is in the pore spaces of the rock
groundwater
empty space in a rock
porosity
concealed space in rocks
rate of water flowing through rock
permeability
high porosity
high permeability
holds water
sandstone
low permeability
no water
Shale
