Geology HW: Chapter 13

Choose the correct pair of terms from the choices below.

A) incised meanders, B) terraces

Which portion of the stream is the most likely to become an oxbow lake in the near future?

D

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.

Velocity and turbulence are _____ at the __________.

greatest; outside of a meander

Match each of the following processes with one of the three zones shown on the figure of a river system.

1. sediment production 2. sediment transport 3. sediment deposition

How did the Mississippi River delta form?

As the Mississippi River enters the Gulf of Mexico, its velocity decreases and it begins to drop its sediment load.

At which of the following locations is deposition occurring?

B, D

Which ocean is Earth's largest?

the Pacific Ocean

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

undercutting and lateral erosion

When do streams erode laterally?

when downcutting is occurring in easy-to-erode sediment or rock

Which of the following statements about deposition and erosion around meander loops is true?

- Deposition occurs where water is moving the slowest along the inside of the loop. - Erosion occurs where water is moving the fastest along the outside of the loop.

Look at the accompanying graph, and read the following statements regarding the time relationship between rainstorms and flooding. Based on this graph, which of the statements are true?

- Flooding correlates with increased stream discharge. - Peak stream flow happens after a storm.

Stream channels have three major zones, from their headwaters to the mouth, and each zone exhibits unique characteristics. Label the zones of a river system based on the dominant process operating within each zone.

- Zone of sediment production - Zone of sediment transportation - Zone of sediment deposition

Direction and location of streamflow controlled primarily by slope:

- peaks surrounded by valleys - peaks surrounded by valleys solid igneous bedrock of uniform composition and slope - layers of solid sedimentary, similar rock

Direction and location of streamflow controlled primarily by geology:

- solid bedrock that is fractured in some areas - areas of hard rocks interspersed with areas of softer rocks

How are oxbow lakes formed?

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

What does the hydrologic cycle describe?

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

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

The oceans would become smaller.

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 a stream terrace?

a remnant of an older floodplain that sits above the stream valley

What is a natural levee?

a ridge of flood deposits next to a river channel

If the velocity of a stream decreases, competence __________ and sediment is _____.

decreases, deposited

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

downcutting

Rectangular

drainage patterns can form where streams flow over rocks that are heavily fractured. Since fractures (joints) often run nearly perpendicular to each other, stream channels in a rectangular drainage pattern join each other at right angles as they follow the fractured, more easily eroded bedrock.

Radial

drainage patterns develop where streams radiate outward from an isolated high area.

Trellis

drainage patterns form where streams flow over alternating bands of harder and softer ground (for example, flowing over folded layers of alternating resistant and less resistant rock). This pattern of erodible and less erodible ground leads to channels that run nearly parallel to one another, connected in breaks in ridgelines. These have the appearance of a garden trellis.

Dendritic

drainage patterns resemble a branching tree. Dendritic patterns are the most common type of stream drainage, and typically form where streams flow over materials that are uniform in their resistance to erosion.

Which of the following are part of the bed load?

gravel, sand

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

ions

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

meandering stream

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

rolling, sliding, bouncing

What is discharge a measurement of?

the amount of water flowing in a river

What is suspended load?

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

Imagine a valley containing four stream terraces. Where would the youngest stream terrace be found?

the lowest terrace

When do stream terraces form?

when streams exist under alternating erosional and depositional conditions

Which of the following statements are true?

A cut bank is located on the outside of a meander bend.

At which of the following locations is erosion occurring?

A, C, E

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

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

What has caused the hypoxic "dead zone" to form off the coast of the Gulf states?

Fertilizers promote the growth of algae. When they die and decompose, oxygen is depleted in the Gulf of Mexico.

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.

How many stream terraces can exist along a single valley?

No limit exists. Stream terraces will keep forming as long as lateral erosion and downcutting continue.

Where are the headwaters of the Mississippi River?

Northern Minnesota

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.

Are stream terraces depositional or erosional landforms?

Stream terraces can be either depositional or erosional.

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

The atmosphere would contain less water.

Water erodes the outside of a river bend to form a __________.

cut bank

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

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

clay