Geology Stream Development and Valleys

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Questions and Answers

What is the region where water first accumulates to supply a stream called?

Watershed

Headwaters (correct)

Stream channel

Mouth

What term describes the narrow pathway carved by moving water into sediment or rock?

Stream channel (correct)

Gully

Stream bank

Erosion path

What is headward erosion?

The creation of stream channels by human activity

Erosion at the beginning of a stream that affects upstream areas (correct)

When a stream widens as it flows downstream

The process of sediment deposition at the stream mouth

What process occurs when one stream captures the water from another?

Stream capture Signup and view all the answers

What represents the slope of a stream channel?

Stream gradient Signup and view all the answers

What is the base level of a stream?

The elevation at which a stream enters another body of water Signup and view all the answers

What can result from the process of stream capture?

Increased water flow to the capturing stream Signup and view all the answers

How do freshwater lakes and wetlands primarily form?

From the accumulation of precipitation in low-lying areas Signup and view all the answers

What is the primary composition of alluvial fans?

Sand and gravel Signup and view all the answers

Which feature forms at the point where a stream enters a large body of water?

Delta Signup and view all the answers

What happens during the process of rejuvenation in a stream?

The stream resumes downcutting and increases in velocity Signup and view all the answers

Natural lakes can form when which of the following occurs?

Stream flow is blocked by sediment Signup and view all the answers

What type of lakes have glacial origins?

Moraine-dammed lakes and kettle lakes Signup and view all the answers

Which of the following describes alluvial fans?

Fan-shaped, sloping depositional features Signup and view all the answers

What is a key characteristic of delta deposits?

They consist mainly of silt and clay particles Signup and view all the answers

Which of the following scenarios would likely lead to the formation of a moraine-dammed lake?

Glacial retreat leaving a blockage of debris Signup and view all the answers

What factor primarily determines the downcutting energy of a stream?

The height of the stream above its base level Signup and view all the answers

Where in a meander does the water experience the greatest velocity?

At the outside of the curve Signup and view all the answers

What commonly forms when a stream cuts off a meander?

An oxbow lake Signup and view all the answers

What occurs along the inside of a meander due to slower water movement?

Deposition of sediment Signup and view all the answers

What happens to sediment transport when streams lose velocity?

Deposition of sediment occurs Signup and view all the answers

How do meanders become more pronounced in a stream?

Due to differences in water velocity Signup and view all the answers

What is the main consequence of water moving faster on the outside of a meander?

Erosion of the streambed Signup and view all the answers

Which of the following processes takes place as a stream flows along a meander?

Erosion on one side and deposition on the other Signup and view all the answers

What primarily determines the longevity of a lake?

Receiving more water than it loses Signup and view all the answers

Which of the following best defines a wetland?

Land covered with water for part of the year Signup and view all the answers

Which type of wetland receives its water primarily from precipitation rather than streams?

Bogs Signup and view all the answers

What role do wetlands play in environmental health?

Filter out pollutants and sediment Signup and view all the answers

What type of wetland is characterized by having larger plants and often being located near streams?

Swamps Signup and view all the answers

How has the area of wetlands in the United States changed since the 1980s?

Increased due to conservation efforts Signup and view all the answers

What types of environments are typically classified as freshwater wetlands?

Bogs, marshes, and swamps Signup and view all the answers

What is a common misconception about bogs?

They receive water from ground sources Signup and view all the answers

Study Notes

Stream Development

Streams begin in headwaters, accumulating water from precipitation in gullies.
Stream channels are the pathways carved into sediment or rock by moving water.
Stream banks contain the flowing water.
Headward erosion is when small streams erode the rock or soil at the head of a stream.
Stream capture occurs when one stream cuts into another, diverting water.
Stream valleys are formed by the energy of water moving down a slope (gradient).
The stream gradient depends on the base level (elevation where it meets another stream or body of water).

Stream Valleys

The height of a stream above its base level impacts its downcutting energy.
Meanders are bends in stream channels caused by moving water.
Water moving along the outside of a meander curve has the greatest velocity.
Deposition occurs on the inside of a meander where water slows.
Oxbow lakes form when a meander is cut off.

Deposition of Sediment

Alluvial fans are fan-shaped deposits of sediment formed when water flows down steep slopes.
Deltas are triangular deposits where streams enter large bodies of water.
Deltas consist mainly of silt and clay particles.

Rejuvenation

Rejuvenation is when a stream resumes downcutting to its base level.
Downcutting increases flow velocity.
Often caused by uplift of land surfaces above previous base levels.

Origins of Lakes

Natural lakes form in low areas or depressions in surface land.
Some form when streamflow is blocked by sediment.
Other types of lakes, like moraine-dammed lakes, cirque lakes, and kettle lakes, develop from glacial activity.

Lakes Undergo Change

Lakes are temporary features in most cases.
The volume of water in a lake can change over time.
Lakes can change through processes like eutrophication.

Freshwater Wetlands

Wetlands are land areas covered with water for parts of the year.
Common types include bogs, marshes, and swamps.
Wetlands play a vital role in water quality improvement.

Eutrophication

Eutrophication is the enrichment of water bodies with nutrients, leading to excessive plant growth.
It can be sped up by excess nutrients in fertilizers.

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Description

Explore the fundamental concepts of stream development, including headward erosion, stream capture, and the formation of stream valleys. Learn about meanders, sediment deposition, and the dynamics of water flow that shape our landscapes.