Chapter 1.3 Physical Environments - Rivers and Valleys

Question 1

A V-shaped valley is fromed when a

Answer 1

river erodes vertically by hydraulic action and corrasion.

Question 2

The first step in the formation of a v-shaped valley is

Answer 2

• A small valley begins to form, weatherng of the land besides the river produces loose pieces of soil and rock.

Question 3

The second step in the formation of a v-shaped valley is

Answer 3

• The soil and rock roll down the sides of the valley and into the river. The river then carries it away.

Question 4

The third and final step in the formation of a v-shaped valley is

Answer 4

The beds and banks of the river are further eroded by rocks as they bounce and scrape along the river bed by corrasion.

Question 5

If a river flows over hard rock and then over a band of soft rock, the soft rock will be worn away leaving the hard rock. This can lead to the formation of a

Answer 5

waterfall

Question 6

The first part of the formation of a water fall begins: Water flows over areas of

Answer 6

hard and soft rock, eroding the soft rock more quickly by hydraulic action. Overtime the hard rock sticks out over the soft rock to form an overhang.

Question 7

The second step in the formation of a waterfall is:

Answer 7

• The Bottom of the waterfall has lots of energy so it erodes the soft rock even further by hydraulic action.
• The water wears away a pluge ppol underneath the waterfall

Question 8

The third step in the formation of a waterfall is:

Answer 8

• Over time the overhang above the plunge pool becomes unstable and collapses.
• The pieces of the heard rock help to erode the plunge pool further by corrasion and are themselves eroded by attrition.
• The waterfall continues to move upstream forming a gorge.

Question 9

A bend in a river is known as a

Answer 9

meander

Question 10

Step 1 in the formation of a meander is:

Answer 10

The course of the river is not as straight as the upper course so the river flows towards the outer bank.

Question 11

Step 2 in the formation of a meander is:

Answer 11

• The river’s energy is concentrated on the outer bank so by hydraulic action and corrasion it is able to erode the bottom of the bank.
• Over time the bank will collapse forming a steep slope called a river cliff.

Question 12

Step 3 in the formation of a meander is:

Answer 12

• On the opposite inner bank the river is much slower it has little energy so deposits some of its load to form a river beach. (deposition)

Question 13

Step 4 in the formation of a meander is:

Answer 13

• Over time the bend becomes more pronounced and is called a meander.
• The river is also eroding sideways (lateral erosion) and widens the valley.

Question 14

Step 1 in the formation of an oxbow lake is:

Answer 14

• The river continues to erode at the outer banks of the meander until the neck of land between them becomes very narrow

Question 15

Step 2 in the formation of an oxbow lake is:

Answer 15

• During a flood when the river has more energy it cuts through the neck and makes a new straighter channel

Question 16

Step 3 in the formation of an oxbow lake is:

Answer 16

• The meander becomes cut off from the new course of the river and is left as an ox-bow lake. Without a water supply it soon dries up.

Question 17

Step 1 in the formation of a levee is:

Answer 17

• When floodwaters spread across the floodplain the spread of the water slows and is no longer able to transport sediment

Question 18

Step 2 in the formation of a levee is:

Answer 18

• As a result coarser sediments such as sand and gravel are deposited at the channel edge, gradually building up into natural ridges or levees after successive floods.

Question 19

Step 3 in the formation of a levee is:

Answer 19

• Levees act like natural embankments and are often strengthened as part of flood rpevention measures.

Question 20

The floodplain is the area of

Answer 20

• allurial (sand&Silt) deposits found beside the river in its lower course.
• When the river floods it deposits the alluvium.
• The smallest particles found at the edge of the floodplain and the largest next to the river.

Question 21

Braiding is the process by which rivers

Answer 21

divide into seperate channels through material being deposited by the river mid-stream.

Question 22

An estuary is the mouth of a

Answer 22

river where it meets the sea

Question 23

A u shaped valley is a valley with very

Answer 23

high, steep sides and a wide flat bottom formed by a glacier flowing through the original valley.

Question 24

On a map a v-shaped valley can be indentified because the contour lines go

Answer 24

right up to the edge of the river

Question 25

Tributaries are

Answer 25

small streams that join onto the main river

Question 26

A confluence is the point where a

Answer 26

tributary meets the main river