Running Water

Question 1

Talus

Answer 1

Eroded rock fragments that accumulate in a fan or cone shape at the bottom of a cliff

Question 2

Landslide

Answer 2

Large mass of rock, soil, and water than moves down a hill all at once

Question 3

Chief method of erosion

Answer 3

Running water: streams, rivers, creeks, rainwater, melting ice, etc.
Water both mechanically chemically wears down the rock or land and then carries particles way

Question 4

How are lakes and ponds formed?

Answer 4

By intersection of the groundwater table and the surface. This can be a true water table or a perched water table sitting on an impermeable rock layer

Question 5

How is a river system created? 5 stages

Answer 5

1. rain flows downhill and forms gullies
2. gullies deepen until they reach source of groundwater
3. permanent stream is formed in the gully if the groundwater supplies water constantly
4. networks of small streams combine to form a larger mainstream
5. mainstreams combine to form a river system (like Mississippi River and its tributaries)

Question 6

tributary

Answer 6

one of the branching streams that supply the mainstream of a river system

Question 7

mouth of a river

Answer 7

the place into which a river empties; usually a large body of water (ocean or lake)

ex: the Hudson river’s mouth is at Manhattan and empties into NY Bay and then into Atlantic Ocean

Question 8

watershed

Answer 8

entire land area drained by a river system

Question 9

Abrasion

Answer 9

Mechanical erosion of bedrock by a stream or river. Pieces of rock are carried by the running water and rub against the bedrock, wearing it down bit by bit

Question 10

River may erode rock by abrasion or by….

Answer 10

Chemical action

Compounds dissolved in streams may wear down rock by dissolving the minerals in the rock

Question 11

4 factors that affect how fast a stream erodes its bed

Answer 11

1. volume of water that flows past a point per unit time
2. type of rock of which the bed is made
3. substances being carried in stream
4. speed of water

Question 12

Why does a quickly moving river erode its bed fast?

Answer 12

It can carry large particles at a high speed, resulting in more power to wear down the river bed

Question 13

Will a stream carrying small fragments of rock erode its bed slower or faster than one carrying large rocks?

Answer 13

Slower. smaller rock has less cutting power because force of collisions with the stream bed is less. Larger rocks with sharper edges erode faster.

Question 14

Whick will erode more easily, a river bed made of shale or slate?

Answer 14

Shale is softer than slate and will erode more easily

Question 15

4 occassions when a stream loses speed

Answer 15

1. ground becomes less steep
2. changes direction (rounds a bend)
3. overflows the bank
4. enters a lake that doesn’t have same forward flow

Question 16

stream deposition

Answer 16

quantity of rock material left behind when a stream loses speed and is no longer able to carry as much rock

Question 17

delta

Answer 17

Rock particles (sediment) collect and create a mass when a river slows down. A delta is formed at the mouth of a river as it flows into a larger body of water (lake, bay, ocean); has the shape of a triangle. Generally good area to grow cops, ie the Mississippi, Nile, and Niger deltas

Question 18

Alluvial fan

Answer 18

Deposit of rock formed when a river flows from high in the mountains into flatter land. It has a triange shape, like a delta. Usually forms in arid areas where there is erratic rainfall and no rivers exist to carry away the sediment.

Question 19

Levee

Answer 19

low wall formed on the banks of a river; created by deposits of material collected every time the river overflows its bank and the flow decreases

Question 20

sandbar

Answer 20

deposit of material along inside bank of a river at a point where river curves. Caused by a slower water velocity at the inside part of curve

Question 21

Qualities of a young river

Answer 21

1. starts at high altitude
2. flows quickly
3. carries many loose rocks
4. erodes a deep and narrow channel
5. waterfalls and rapids are present

Ex: Colorado River

Question 22

Qualities of a mature river

Answer 22

1. eroded channel with few waterfalls in wide valley
2. channel is wide
3. slower speed of water
4. carries fine grained sediment
5. developing flood plain

Ex: Ohio River

Question 23

Qualities of an old river

Answer 23

1. flows slowly
2. broad flood plain (flat river valley)
3. high levees

Ex: lower part of Mississippi River

Question 24

Meander

Answer 24

s-shaped curve found in a mature river

Question 25

How is a meander formed?

Answer 25

Formed when the river flows around an obstruction, rather than eroding it

Question 26

Flood plain

Answer 26

Materials carried by river are deposited in valley after flood. Eventually a large, flat area is formed. Flood plain can become a swamp if there is nowhere for flood water to drain

Question 27

2 ways to form a waterfall

Answer 27

1. Unequal erosion: rocks of different hardness make up the river bed; over time the soft rock erodes more quickly, leaving a drop (Yellowstone falls, Niagara Falls)
2. Glacier cuts off a valley, leaving it hanging; the stream flowing in the hanging valley falls to the glaciated valley floor