Ice ages, glaciers

Ice ages, glaciers

Ice ages, glaciers, glacial landforms and glacial sediments are vital topics of study since they entail many features surrounding the living organisms. However, its effect is invisible if it affects us as humans indirectly. This assignment will entail several activities and findings such as glaciation, glacial landforms and sedimentation, and its effects on the landscape.

In this topic, there are several steps involved in the glaciation formation process. Glaciation is the process where glaciers are formed, move and depressed. The glaciation process occurred frequently compared to the present time since a larger portion of the world was covered with large continental ice sheets. Glaciers currently cover 10% of the world’s land cover. This paper addresses several issues such as the definition of key terms, how glaciers change the landforms, features formed by glaciers, how glaciers affect the landscape, the locations or places where glaciers are evident.

According to History.Com Editors (2019) ice age is the duration of low temperatures on the Earth’s surface, resulting in glacial expansion. It can last more than hundreds of millions of years. There have been at least five significant ice ages in the earth’s history, with approximately twelve ages of glacial expansion occurring in the past 1 million years. Despite the moderate temperatures in the Antarctic and Greenland ice sheets, the earth’s surface remains intact, currently during the ice age.

Glaciers are referred to as moving ice, and they are made up of more than just ice and snow. The glaciers contain water, rocks and sediments. The glacier is a considerable continuous accumulation of crystalline ice and snow resulting in the formation of a large mass of snow, and due to the influence of the weight that it carries and gravitational force, the bottom part of the glacier starts to melt and start moving down the slope (USGS,).

Glaciers are grouped according to the different features such as their size, location and thermal regime. Glaciers classified according to size include: ice sheets, ice caps, valley glaciers, cirque glaciers and those classified according to thermal regime include: polar versus temperature.

Glacial landform they are the features formed by glaciers. Such features are mostly found in the glaciated areas such as Greenland, Antarctica, and high mountain ranges.

Glacial sedimentation is also referred to as a glacial deposition.  As the glacier moves down the slope, some sediments are deposited hence settling. The meltwater at the bottom of the glacier can also form a bedrock when they freeze. When debris and rocks from mountains fall on the glacier surface, they even sediment.

How glacier changes the landforms, how different features are formed, its effect on soil and soil erosion.

There are different types of glaciers, and the different types of glaciers form different features. Continental glacier is one type of glacier that covers large parts of continents, and the other type of glacier is an alpine glacier found in the mountainous regions. Glaciers are important agents of erosion. Continental glaciers erode the land surface as they flow down the slope forming flat plains, and alpine glaciers create a wide variety of different forms. Some of the critical features formed by alpine glacial erosion include;

Cirques

Prof. Stephen A. Nelson (2015) defined cirques as a bowl-like depression at the peak of a mountain glaciers. Its resultant features include; frost wedge, glacial plucking, and abrasion. At the depression of the cirque, small lakes called tarns can be formed after the glaciers’ retreat.

The image above shows a cross-section of a glacial cirque showing a depression with a lake-filled valley floor and a steep headwall with slope deposits. The image was from the Jacob Bendle (2020).

Cirque is formed through a gradual expansion of mountainside hollows associated with earlier fluvial, volcanic or mass movement activities. The depression then gets filled with snow and enlarges due to some processes such as freezing, chemical weathering and snowmelt. Cirque growth happens when the thickness of snow increases to a point at which glacier ice can form by compaction.

The image above shows a glacial cirque basin of mountain Glyderau in Snowdonia. From Jacob Bendle (2020).

U-Shaped Valleys, Fjords, and Hanging Valleys

U-shaped valleys are formed through glacial erosion. When glaciers start to flow downslope, they tend to take the easiest path hence occupying the V-shaped valleys. As it flows through the valley, they erode the walls, flattening its floor and forming steeps sides. After the glacier has moved and left the valley, it leaves behind a U-shaped valley.

An image of a U-shaped valley with steep slopes, part of the Cardillera Blanca, a mountain range in Peru, South America. Source

Fjords are the narrow inlets into the oceans set in a U-shaped valley with steep rock walls on both sides. They are usually set in a U-shaped valley. The main areas where found include; Chile, Norway, New Zealand, Canada, the U.S state of Alaska and Greenland. An example of a fjord is Sognefjorden of Norway, which is more than 160 kilometres long.

Hanging valleys are formed after glaciers have retreated. After the glacier has melted, the smaller tributary glaciers erode their trough less rapidly than the main tributaries. Due to this mismatch of erosion, the tributaries trough are left as handing valleys. An example is that of California, known as Yosemite Falls.

Yosemite Falls image of California.

Summary

Bendle, J. (2020, Octomber 5). Cirques. Retrieved from Antarctic Glaciers.org: http://www.antarcticglaciers.org/glacial-geology/glacial-landforms/glacial-erosional-landforms/cirques/.

Editors, H. (2019, July 7). Ice Age. HISTORY. Retrieved from https://www.history.com/topics/pre-history/ice-age.

USGS (2019). What is a glacier? Usgs.gov

https://www.usgs.gov/faqs/what-a-glacier