PS chp 22 HW

What types of soil allow the greatest amount of rainfall to soak in?

sandy soil with good hydraulic conductivity

Under what conditions do curvy, meandering rivers form along a floodplain?

when a river slows changing from eroding downward to eroding side-to-side

If the cross-sectional area of the stream is 0.50 m2m2 and the stream speed is 0.46 m/sm/s , what is the stream's discharge?

.23 m^3 /s

in streams lake a rivers?

.32

If the cross-sectional area of the stream increases to 2.5 m2m2 and the stream speed remains 0.46, what is the stream's discharge?

1.2 m^3 /s

In groundwater?

22

How is a glacier formed?

A glacier is formed when snowfall is compacted into ice that flows under its own weight

List, the following types of sediment in order of deposition: (a) boulders and cobbles, (b) pebbles and gravel, (c) sand, (d) clays and mud.

ABCD

Under what conditions does a glacier front advance? Under what conditions does it retreat?

Advance: when accumulation exceeds ablation Retreat: when ablation exceeds accumulation

How much of Earth's surface water exists in the oceans?

Almost all of Earth's surface water exists in the oceans.

What is an artesian system and how is it formed?

An artesian system is a confined aquifer. The aquifer is sandwiched between low-permeability layers with water pressure from water above forcing water to flow out of the ground.

What would happen to atmospheric water if Earth were mostly covered with land?

The atmosphere would contain less water.

What would happen to the oceans if surface runoff and groundwater flow did NOT occur?

The oceans would become smaller.

What happens to stream speed when the discharge of a stream increases?

The stream speed usually increases, but if the channel geometry changes the speed could actually slow down.

Compare and contrast the unsaturated zone with the saturated zone.

The unsaturated zone has pores partially full of water; the saturated zone has pores filled with water.

How does the water table change around a pumping water well?

The water table elevation decreases.

Which transports more sediment: a laminar flow or a turbulent flow? Why?

Turbulent flow because it lifts particles into the flow and slides them along the channel.

What factors are responsible for the formation of a stream valley?

Water erodes material forming a channel, and gravity pulls material downhill on either side of the channel creating a V-shaped valley. The stream carries away sediments.

How do sand dunes migrate?

Wind blows sand grains from the windward to the leeward slope

Why do dunes migrate?

Wind erodes material on the back side of the dune and deposits it on the front side of the dune.

Although glaciers are a frozen ice mass, they flow due to _______.

pressure and plastic flow, and basal sliding

How can pieces of rock in contact with a stream bed move?

rolling, sliding, bouncing

How do pieces of rock move under the influence of wind?

rolling, sliding, bouncing, suspension

Which of the following are part of the bed load?

sand and gravel

What property of a piece of material will most directly determine how it is carried by wind?

size

In what two main ways do glaciers flow?

sliding downslope and internal plastic deformation

What do cross beds represent?

the moving front of a ripple or dune

What is dust?

the particles carried in suspension by wind

What is the cone of depression?

the shape that the water table takes on near a pumping well

Which of the following statements is true about erosion?

Erosion varies from place to place.

Where does most of Earth's precipitation occur?

over oceans

What is suspended load?

the fine-grained particles that travel in the water column above the stream bed

Which processes result in the widening of the floodplain of a meandering stream?

undercutting and lateral erosion

When will a cone of depression stop enlarging?

when the amount of water flowing toward the well equals the amount of water being pumped out of the well

When might a well, Well A, go dry?

when the cone of depression of a second well intersects the deepest part of Well A

A stream's erosive power is greatest _______.

where discharge and velocity are greatest

Below the ground, water moves from _______.

where the water table is high to where the water table is low

As a stream moves downslope, the gradient gradually decreases and the channel _______.

widens and discharge increases

How do sand dunes migrate?

windward slope saltation, leeward slope avalanching

How do stalactites and stalagmites form?

Stalactites form as water containing calcium carbonate drips from the roof of a cave and evaporates leaving behind limestone; stalagmites form on the floor of the cave by the same process.

What does the hydrologic cycle describe?

The hydrologic cycle describes how liquid and gaseous water move between the ocean, atmosphere, and land.

What erosional features are likely found in an area of alpine glaciation? (See Figure 22.37a).

U-shaped valleys, cirques, and horns

Where do valleys tend to form in a landscape?

Valleys form where rock layers are easily erodible (soft).

What is a natural levee?

a ridge of flood deposits next to a river channel

Where is most of Earth's freshwater found?

as ice at Earth's surface

What are the three types of loads carried by streams?

bed load, suspended load, dissolved load

How are ripple marks formed?

by lift and deposition of sand grains by wind or flowing water

Name three erosional features caused by groundwater in carbonate rocks.

caves, caverns, and sinkholes

What three variables influence the speed of stream flow?

channel geometry,stream discharge,stream gradient

Describe three ways that flowing water erodes a stream channel.

chemically, hydraulically, and by abrasion

Complete this analogy: Bouncing is to sand as suspension is to_____________.

clay

What types of streams and stream valleys do we generally find in high, mountainous regions?

fast-moving streams with rapids and V-shaped valleys

Streams transport great quantities of sediment from one place to another. What is the size range of the particles that can be carried by a fast-moving stream?

from the smallest particles of clay to large pebbles and cobbles

The three variables that influence the speed of stream flow are _______.

gradient, discharge, and channel geometry

Sand dunes can form _______.

in an area where wind-blown sand grains are blocked by an obstacle

What are cross beds?

inclined layers in sediment or sedimentary rocks that reveal the direction of wave or wind transport

Complete this analogy: Sliding is to gravel as dissolution is to_____________.

ions

The overpumping of groundwater can result in _______.

land subsidence and sinkholes

Describe the consequences of over-pumping groundwater.

land subsidence; wells go dry

What type of stream is associated with the formation of an oxbow lake?

meandering stream

What is the most common depositional landform created by glaciers?

moraines

What land features are formed from glacial deposits?

outwash plains

The amount of water the ground can hold, and the ability of the ground material to allow water movement, are called _______.

porosity and hydraulic conductivity

Scientists can determine the direction of ancient ice movement by looking for _______.

striations, roches moutonnées, and drumlins

Which ocean is Earth's largest?

the Pacific Ocean

What is the difference between a cave and a cavern?

Caverns are large caves.

In descending order, rank the rocks in terms of their susceptibility to chemical erosion: (a) marble, (b) limestone, (c) sandstone, (d) quartzite.

BACD

Put in order, from beginning to end, the steps in stream formation: (a) runoff forms, (b) raindrops strike the ground, (c) water begins to run downslope, (d) gullies form

BACD

Rank, from greatest to least amounts, the distribution of Earth's freshwater: (a) groundwater; (b) polar ice caps and glaciers; (c) streams, rivers, and lakes; (d) soil moisture.

BACD

Rank, from first to last, the stages in glacial flow: (a) basal sliding, (b) crevasses, (c) accumulation and thickening of glacial ice, (d) calving.

CABD

How does rainwater naturally become acidic? How does this affect limestone?

Carbon dioxide in the air creates carbonic acid in water that dissolves limestone.

What is the relationship between water currents and cross beds?

Cross beds sit at an angle to current direction

Where do deposition and erosion of material occur along a meander?

Deposition occurs on the inside of the meander, whereas erosion occurs on the outside.

What is stream gradient, and how does it affect stream velocity?

Gradient is the drop divided by the distance; the greater the gradient the faster the stream.

If a hole is dug in the unsaturated zone, does it fill with water? Why or why not?

It does not fill with water because pores are only partly full of water.

As water is precipitated onto the land, where does it go? Where does most of the water on land end up?

It goes to the ocean; most water ends up in glaciers and ice caps.

How does water get from the oceans onto land?

Ocean water evaporates to form gaseous water and moves into the atmosphere, where it condenses into liquid water and falls out of the atmosphere to land as rain.

How are oxbow lakes formed?

Oxbow lakes form when one meander erodes into another, cutting off water to part of the stream channel.

Distinguish between porosity and hydraulic conductivity.

Porosity is the volume of pore space in soil; hydraulic conductivity measures the ability of water to move through soil.

How does the shape of a stream channel affect flow?

Rounded, deep channels have less friction and higher speed than shallow, flat-bottomed channels.

What is a delta?

a fan-shaped deposit of sediment where a river meets a sea

What is a floodplain?

a flat surface next to a river channel

What is a meander scar?

a landscape feature formed after an oxbow lake dries up

What is an oxbow lake?

a meander that has been cut off from the original stream channel

What is the dominant fluvial process in a clear, sediment-poor stream moving down a steep slope?

downcutting

The dominant processes in the hydrologic cycle are _______.

evaporation and precipitation

Of this freshwater supply, what percentage is found in the polar ice caps? HintHint: Calculate the freshwater supplies to be equal to 100%.

77%

How does the formation of a natural levee impact flooding?

Natural levees raise the height of the stream channel, reducing the amount of flooding that will occur on the floodplain.