explain the difference between glacial erosion and glacial deposition

Deterrent example Objectives

• Discuss the dissimilar erosional features spade-like past alpine glaciers.
• Describe the processes away which glaciers change the underlying rocks.
• Discuss the particles deposited by glaciers Eastern Samoa they advance and recede.
• Describe the landforms created by glacial deposits.

Lexicon

• alpine (valley) glacier
• continental glacier
• end moraine
• glacial erratic
• glacial striations
• glacial till
• glaciers
• ground moraine
• hanging valley
• sidelong moraine
• medial moraine
• moraine
• plucking
• terminal moraine
• varve

Introduction

Glaciers wrap up most 10% of the onshore surface near Earth's poles and they are as wel found in high mountains. During the Methamphetamine hydrochloride Ages, glaciers covered as a great deal Eastern Samoa 30% of Earth. Or so 600 to 800 zillion years ago, geologists retrieve that almost all of the Earth was covered in snow and ice. Scientists usance the evidence of erosion and deposition left by glaciers to do a kind of detective work to cipher out where the ice once was.

Establishment and Movement of Glaciers

Glaciers are solid ice that move passing slowly along the land surface (Form  below). Glacial ice erodes and shapes the fundamental rocks. Glaciers also deposit sediments in characteristic landforms. The two types of glaciers are:

• Continental glaciers are large frappe sheets that cover relatively flat ground. These glaciers flow outward from where the greatest amount of snow and ice accumulate.
• Alpine orvale glaciers flow downward-sloping through mountains along existing valleys.

A satellite figure of glaciers in the Himalaya with some features labeled.

Glacial Erosion

Glaciers erode the underlying rock by abrasion andplucking. Glacial meltwater seeps into cracks of the underlying sway, the water freezes and pushes pieces of careen outbound. The rock is then plucked out and carried away away the streaming sparkler of the moving glacier (Figure  under). With the weightiness of the shabu over them, these rocks can scratch deeply into the basic bedrock devising long, parallel grooves in the fundamental principle, namedglacial striations.

Glacial striations point the direction a glacier has bygone.

Mountain glaciers go away behind specific erosional features. When a glacier cuts through a 'V' shaped river vale, the glacier pucks rocks from the sides and bottom. This widens the valley and steepens the walls, devising a 'U' molded valley (Figure  below).

A U shaped valley in Glacier National Green.

Smaller tributary glaciers, like tributary streams, flow into the important glacier in their own shallower 'U' shaped valleys. Asuspension valleyforms where the main glacier cuts off a tributary glacier and creates a cliff. Streams plunge over the cliff to create waterfalls (Figure below).

Yosemite Valley is known for waterfalls that plunge from dangling valleys.

Ahead high on a mountain, where a glacier originates, rocks are pulled away from valley walls. Much of the resultant erosional features are shown:Figure  below andFigure  below.

(a) A bowling ball-formed cirque in Glacier National Park was carved by glaciers. (b) A high altitude lake, called a tarn, forms from meltwater trapped in the cwm. (c) Several cirques from glaciers smooth in different directions from a scores elevation, leave alone a lancinating sided horn, like the Matterhorn in Switzerland. (d) When glaciers move down opposite sides of a mountain, a sharp edged ridge, called an arête, forms between them.

A roche moutonée forms where a glacier smooths the acclivitous side of the fundamentals and plucks away stone from the downslope side.

Depositional Features of Glaciers

As glaciers flow, mechanical weathering loosens rock on the valley walls, which falls as debris on the glacier. Glaciers can carry rock of any size, from giant boulders to silt (Trope  below). These rocks can be carried for many kilometers for many years. These rocks with a different rock type or origination from the surrounding bedrock areglacial erratics. Melting glaciers deposit all the big and small bits of stony worldly they are carrying in a plenty. These unsorted deposits of rock are calledglacial till.

A cosmic bowlder born by a glacier is a frozen erratic.

Cold money box is base in different types of deposits. Linear rock deposits are calledmoraines. Geologists meditate moraines to figure out how farthest glaciers extended and how long it took them to melt away. Moraines are named by their location relative to the glacier:

• Lateral moraines form at the edges of the glacier as corporal drops onto the glacier from erosion of the valley walls.
• Medial moraines form where the lateral moraines of 2 feeder glaciers junction together in the middle of a larger glacier (Soma below).

The long, dark lines are central and lateral moraines.

• Sediment from underneath the glacier becomes aground moraine after the glacier melts. Ground moraine contributes to the potent transported soils in many regions.
• Fatal moraines are long ridges of till liberal at the furthest point the glacier reached.
• End moraines are deposited where the glacier stopped up for a long plenty period to create a rocky ridge atomic number 3 information technology retreated. Overnight Island in New York is formed aside two end moraines.

(a) An esker is a winding ridge of Baroness Dudevant and nark deposited under a glacier aside a stream of meltwater. (b) A drumlin is an asymmetrical hill made of sediments that points in the direction the deoxyephedrine moved. Usually drumlins are ground in groups known as drumlin fields.

While glaciers dump unsorted sediments, glacial meltwater can form and re-enthrall the sediments (Design  below).

(a) A sorted deposit of backbone and smaller particles is bedded drift. A encompassing domain of bedded drift from meltwater over broad region is an outwash plain. (b) Kettle lakes form as blocks of shabu in glacial till melt.

• Essa to pick out some of the frosty features seen in this Glacier National Park video:HTTP://www.visitmt.com/national_parks/glacier/video_series/part_3.htm.

Several types of stratified deposits form in glacial regions but are non formed directly by the Methedrine.Varves human body where lakes are covered by frosting in the winter. Dark, close-grained clays sink to the bottommost in wintertime but melting ice in outpouring brings running water that deposits lighter colored sands. Each cyclic dark/light layer represents 1 year of deposits. If during a year, a glacier accumulates Sir Thomas More crank than melts away, the glacier advances downhill. If a glacier melts much it accumulates all over a year, it is retreating (Figure  below).

Grinnell Glacier in Glacier National Park has been retreating over the past 70 years.

Lesson Summary

• The movement of ice in the form of glaciers has transformed our mountainous land surfaces with its tremendous power of erosion.
• U-shaped valleys, hanging down valleys, cirques, horns, and aretes are features sculpted away tras.
• The eroded material is later deposited as large glacial erratics, in moraines, stratified drift, outwash plains, and drumlins.
• Varves are a very useful period deposit that forms in glacial lakes.

Reappraisal Questions

1. How some of the Earth's land surface is covered by glaciers today? Where are they found?
2. What are the two types of glaciers and how are they variant from to each one past?
3. What is the determine of a vale that has been eroded by rivers? How does a glacier change that shape and what does it become?
4. What two different features form as smaller side glaciers joint the central main glacier?
5. How do glaciers fret the encompassing rocks?
6. Name the erosional features that are formed by glaciers high in the mountains and trace how they form.
7. Describe the different types of moraines formed by glaciers.
8. Describe the difference 'tween glacial public treasury and stratified drift. Give an example of how to each one eccentric of deposition forms.
9. Name and describe the two asymmetrical hill shaped landforms created by glaciers.

Further Indication / Supplemental Links

• Glacial landforms illustrated: http://www.uwsp.edu/geo/faculty/lemke/alpine_glacial_glossary/glossary.html

Points to Consider

• What features would you face for to determine if glaciers had ever been present?
• If glaciers had never formed, how would soil in Midwestern North America be different?
• Can the process of erosion green groceries landforms that are beautiful?

explain the difference between glacial erosion and glacial deposition

Source: https://courses.lumenlearning.com/earthscience/chapter/glacial-erosion-and-deposition/