5-2 Notes: Water Erosion
Streams Shape Earth’s Surface
 What do you notice these three streams all have in
common?
 You probably noticed (among other things):
o The land is ______________________
than the water
o The land is sloping down to the water
o The water is moving _______________
 Running water is the major agent of erosion
shaping the landscape of ______________________.
 Running water shapes _________________________
by moving sediment in the processes of erosion and
deposition.
 A ___________________________ is a body of water
-large or small-that flows down a slope along a channel.
Drainage Basins and Divides
 Streams flow into one another to form complex systems.
 ______________________ streams flow into larger ones.
 The area of land in which water drains into a stream system is called a
drainage ________________________.
 Most drainage basins eventually drain into a lake or _______________.
o Example: the Mississippi River drainage basin empties into the
Gulf of Mexico.
 Drainage basins can be a few __________________________ wide or
can take up a large portion of a continent.
 Drainage basins are separated by ridges called ___________________
-a ridge from which water drains to one side or the other.
Valleys and Floodplains
 As streams flow and carry sediment, they form ____________________________.
 In high mountains, streams often cut _______-shaped valleys that are narrow and steep.
 In lower areas, streams may wide broad valleys that include _________________________________-an area of
land on either side of a stream that is underwater when the stream floods.
 When a stream floods, it deposits the _____________________________ it carries onto the floodplain.
 This makes floodplains very fertile-able to support a lot of plant growth.
 The floodplains of the Mississippi river are some of the best places for growing _______________ in the U.S.
Stream Channels
 As a stream flows through a valley, its channel may run straight in some
parts and curve in other parts.
 Curves and bends that form a twisting, looping pattern are called
_____________________.
 Over many years, meanders can change position and get ____________
from the rest of the stream.
 A cut-off meander forms a _______________________ shaped lake called
an oxbow lake.
Alluvial Fans and Deltas
 Alluvial fan- a fan-shaped deposit of sediment at the base of a _______________________ created by a stream.
p. 79
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Alluvial fans are formed when a ________________________ leaves a steep valley and enters a flatter plain.
_______________________- an area of land formed by the buildup of sediment at the end of a river.
Over time, a delta builds up into a fan-shaped ______________________.
Over a very long time, a river can build up a huge delta that reaches out to ____________.
Water Moving Underground Forms Caverns
 Not all rainwater runs off the land and flows into streams.
 Some of it evaporates, some is absorbed by plants, and some soaks into the ground to become groundwater.
 At a certain depth below the surface, the spaces in soil and rock become completely filled with water.
 The top of this region is called the _________________________________________.
 Water below the water table is called groundwater.
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As groundwater flows through rock and soil, it causes ___________________________.
Groundwater erosion causes certain rocks (like limestone) to dissolve.
Over time, this process produces open spaces in rock called ______________________.
Very large caves are called _____________________________.
Sinkhole- a basin formed when the roof of a cave suddenly falls in
Review
____1. A sinkhole is formed by the collapse of
A. an alluvial fan
B. a cavern
C. a moraine
D. a kettle lake
____2. Rivers transport sediment to
A. Drainage basins
B. Oceans and lakes
C. The water table
D. Moraines
____3. Drainage basins are separated by a
A. moraine
B. divide
C. tributary
D. barrier island
____4. In high mountains, a valley carved by a stream has the shape of a
A. U
B. Crescent
C. Plate
D. V
____5. An oxbow lake is formed by the cutting off of a
A. meander
B. drainage basin
C. sinkhole
D. glacier