science turn down
Meander
A looplike bend in the course of a river
Fast moving:
A lot of sediments of various sizes
What is meant by watershed (drainage basin)?
all of the land where rainfall drains into the main river or one of it's tributaries
Exfoliation
as underlying rock layers are exposed, there is less pressure on them and they expand which causes the rigid layers to crack and sections to slide off
how it is transported: boulders
bedload
how it is transported: pebbles
bedload
how it is transported: sand
bedload
shape of valley old age
broad u shaped
Frost wedging
cracking of rock mass by the expansion of water as it freezes in crevices and cracks
nature of meanders maturity
curves
youth type of erosion
downcutting
Amount of uplands in old age
flat
amount of discharge maturity
greater than youthful river
Amount of uplands in maturity
hills
how it is transported: calcium
in solution
How do streams transport sediments?
in solution, in suspension, bedload
maturity type of erosion
lateral
old age type of erosion
lateral
size of sediments maturity
medium-small sediments
maturity slope or gradient
moderate
Amount of uplands in youth
mountains
abraision
moving sediments or rock sections can break off pieces from a rock surface they strike
amount of discharge old age
quite large
bedload
sediment are bouncing along the bottom of the river
old age slope or gradient
shallow
size of sediments old age
small sized
size of sediments youth
smalle - large
how it is transported: magnesium
solution
youth slope or gradient
steep
nature of meanders youth
straight
how it is transported: clay
suspension
how it is transported: fine sand
suspension
how it is transported: silt
suspension
Steam channel
the course the water in a stream follows.
nature of meanders old age
the most curves
Erosion
the transportation of weathered material from location a to location b
Discharge
the volume of water flowing past certain point in a given unit of time
amount of discharge youth
very low
Mechanical Weathering
when physical forces break rock into smaller and smaller pieces without changing the rock's mineral composition Physical weathering
Chemical weathering
when rocks and minerals undergo changes in their composition because chemical bonds between atoms are broken, rearranged etc
headwaters of a river?
where a river starts
mouth of the river
where the reverends
Gradient
A slope
What is the relationship between a stream and a drainage basin?
A stream discharges into a drainage basin. A drainage basin is a tract of land drained by a river and its tributaries.
Talus
An accumulation of rock debris at the base of a cliff.
What factor most influences the power of a stream to erode and transport material?
Gradient
What is velocity?
How fast a river is moving
How does chemical weathering affect the compounds in a rock?
It changes them
What happens to a rock's mineral composition during mechanical weathering?
It stays the same
What is unloading? How does it contribute to weathering?
Large masses of igneous rock may be exposed through uplift and erosion of overlying rocks. When that happens, the pressure exerted on the igneous rock is reduced. This increases the surface area of the rock. The increase in surface area allows for an increase in chemical weathering.
Slow moving:
Less sediments that tend to be smaller
How might lowering base level affect stream erosion?
Lowering base level increases the vertical distance between the source and destination increasing energy.
Base level
Lowest elevation to which the stream can erode downward, for many streams, the water surface level of the body of water into which they flow
More discharge means
More sediments that can be carried
deposition
Process in which sediment is laid down in new locations.
Name two rock characteristics and two climatic factors that affect the rate of weathering
Rock chemistry, and size. Temperature and wind.
In solution
Sediments are dissolved
In suspension
Sediments are floating the entire time
What affects the speed of weathering?
Surface exposure: the more of a rock that is shown to the environment, the quicker the rock is weathered composition: Sedimentary rocks usually weather quicker than igneous and metamorphic climate: amount of water present and temperature differences
How do gradient and discharge change between a steam's headwaters and its mouth?
The gradient gets less steep. The discharge get bigger.
What is a divide?
The high land that seperates one watershed from another
shape of valley maturity
U shaped
shape of valley youth
V shaped
What are the factors that determine the amount and size of sediments?
Velocity, gradient, discharge
HIgh gradient
Water moves faster, and there are more sediments
Low gradient
Water moves slower, and there are less sediments
Tributary
a stream that runs into a bigger stream or river
How do streams erode their channels?
abrasion, grinding, and by dissolving soluble material.
