Glaciers: Formation, Types and Impact on Earth

Glaciers Glaciers are large bodies of ice that form from the accumulation and compaction of snow over time. They are found in polar regions, such as Antarctica and Greenland, as well as in high-altitude mountainous areas. Glaciers are dynamic and constantly moving, flowing under the influence of gra...

Glaciers Glaciers are large bodies of ice that form from the accumulation and compaction of snow over time. They are found in polar regions, such as Antarctica and Greenland, as well as in high-altitude mountainous areas. Glaciers are dynamic and constantly moving, flowing under the influence of gravity. Glaciers can range in size from small ice patches to massive ice sheets that cover thousands of square kilometers. Glaciers are formed through a process called glaciation. Snowfall accumulates and compacts over time, transforming into dense glacial ice. As the ice mass grows, it begins to flow downhill due to its own weight, creating a glacier. Glaciation refers to the buildup and movement of ice on the earth's surface and the resulting formations and scars left on the ground and in mountain ranges. A formal definition of glaciation is the forming, existence, or movement of glaciers over the surface of the earth. Glaciers play a crucial role in Earth's climate system, as they store significant amounts of freshwater. They also have a significant impact on the landscape, shaping valleys, carving out cirques and U-shaped valleys, and leaving behind distinctive landforms such as moraines, drumlins, and fjords. Due to climate change, many glaciers around the world are retreating and losing mass at an accelerated rate. This has widespread implications for water resources, ecosystems, and sea-level rise. Overall, glaciers are remarkable natural features that provide insights into Earth's history, climate, and geology. The two main types of glaciers: A. Continental glaciers are flatter, massive areas of ice that cover huge sections of land. B. Alpine glaciers are found in mountains and valleys There are several types of glaciers, each characterized by its size, shape, and location. Here are some of the main types of glaciers: 1. Valley glaciers - also known as alpine glaciers or mountain glaciers, are found in mountainous regions and flow down valleys. - They typically have a long, narrow shape and are confined by the surrounding mountain slopes. - Valley glaciers can range in size from small ice patches to large glaciers that extend for several kilometers. - 2. Ice Sheets - also known as continental glaciers, are massive ice bodies that cover large areas of land. - They are found in polar regions, such as Antarctica and Greenland. Ice sheets are characterized by their vast size and relatively flat topography. - - They can be several kilometers thick and can extend for thousands of kilometers. 3. Ice Caps  - these are smaller versions of ice sheets and are found in high- altitude regions. - They cover smaller areas compared to ice sheets but still exhibit the same dome-shaped topography. 4. Cirque glaciers – they are small, bowl-shaped glaciers that form in high mountain cirques, which are amphitheater-like depressions on the mountainside. -they are usually found at the head of valleys and are formed by the accumulation of snow and ice in these sheltered areas. 5. Piedmont Glaciers - they occur when a valley glacier spills out onto a flat plain or lowland area. As the glacier spreads out, it becomes broader and shallower. - they are often characterized by a lobe-like shape and can be found at the foot of mountain ranges. 6. Tidewater glaciers -they are valley glaciers that flow into the ocean or a large body of water. - These glaciers often terminate in a calving front, where chunks of ice break off and form icebergs. Tidewater glaciers are commonly found in fjords and coastal areas. 7. Hanging glaciers - they are smaller glaciers that are suspended on the slopes of mountains. - They typically occupy cirques or small valleys and are characterized by their steep, cliff-like terminus. Like flowing water, flowing ice erodes the land and deposits the material elsewhere. Glaciers are incredibly powerful agents of erosion. Valley glaciers create very distinctive landforms like horns, cirques, and hanging valleys. Glacial erosion is the deformation of Earth's surface after a glacier has traveled over it. A glacier can pluck up and carry rocks, grind and abrade rocks and ice as it moves, and carve out features on the land as it passes through. Glacier erosion happens when so much snow and ice form on the glacier that the weight causes the glacier to move downhill. When the glacier moves downhill, it causes glacial erosion to occur beneath it Glaciers cause erosion in two main ways: plucking and abrasion. Glacial plucking happens when the melting and freezing of glacial ice breaks apart the rock underneath the glacier. As the glacier moves, it plucks those rocks up and moves them with it. Plucking is the process by which rocks, and other sediments are picked up by a glacier. They freeze to the bottom of the glacier and are carried away by the flowing ice. Abrasion is the process in which a glacier scrapes underlying rock. The sediments and rocks frozen in the ice at the bottom and sides of a glacier act like sandpaper. They wear away rock. They may also leave scratches and grooves that show the direction the glacier moved. These grooves are called glacial striations. Glacial abrasion happens as those plucked rocks and glacial ice move across various surfaces causing grinding and scratching to occur. Glacial Deposition As the glacier melts or sublimates, all the sediment carried in the glacier is freed from the ice as it recedes. Grains transported by ice, unlike those transported by water, are not sorted by size (though streams of meltwater may sort and transport the sediment after deposition). Once this pile of sediment is cemented into a rock, the result is a diamictite, a sedimentary rock made up of unsorted grains. A more specific name for an unsorted sedimentary rock with grains deposited by ice is a tillite. The loose sediment is called till in its unlithified form. Moraines A moraine is a ridge-shaped mound of till those forms as a glacier recedes. There are different types of moraines that are named depending on which part of the glacier the sediment comes from.  A terminal moraine is a moraine that forms at the edge of a glacier's farthest extent. As the glacier melts and recedes, recessional moraines will form upslope from the terminal moraine, on land that was once covered by the glacier.  Moraines also form along the sides of a retreating glacier; these are known as lateral moraines. Sediment tends to gather on the sides of glaciers from erosion or mass wasting of glacial valley walls. If there was a sediment-rich band in the center of the glacier, this will form a medial moraine. Such bands form when two tributary glaciers join together.  In the space the receding glacier once occupied within the moraines, the bedrock is covered by a thinner layer of till called a till sheet or ground moraine. Drumlin, oval or elongated hill believed to have been formed by the streamlined movement of glacial ice sheets across rock debris, or till. The name is derived from the Gaelic word druim (“rounded hill,” or “mound”) and first appeared in 1833. Moraine, accumulation of rock debris (till) carried or deposited by a glacier. The material, which ranges in size from blocks or boulders (usually faceted or striated) to sand and clay, is unstratified when dropped by the glacier and shows no sorting or bedding. A fjord is a long, deep, narrow body of water that reaches far inland. Fjords are often set in a U-shaped valley with steep walls of rock on either side. Fjords are found mainly in Norway, Chile, New Zealand, Canada, Greenland, and the U.S. state of Alaska. Sognefjorden, a fjord in Norway, is more than 160 kilometers (nearly 100 miles) long. In general, it is felt that ice ages are caused by a chain reaction of positive feedback triggered by periodic changes in the Earth's orbit around the Sun. These feedbacks, involving the spread of ice and the release of greenhouse gases, work in reverse to warm the Earth up again when the orbital cycle shifts back. The Ice Age, also known as the Pleistocene Epoch, was a period of geological time that lasted from about 2.6 million years ago to 11,700 years ago. It was characterized by the widespread presence of glaciers and extensive ice sheets covering large portions of the Earth’s surface. The Ice Age had a significant impact on the Earth’s climate, geography, and ecosystems. During the Ice Age, global temperatures were much colder than they are today, resulting in the formation of glaciers and ice sheets. These massive ice masses covered vast areas of land, including much of North America, Europe, and Asia, as well as parts of South America and Australia. The weight of the ice caused the Earth’s surface to depress, creating deep valleys and shaping the landscape as we see it today. The Ice Age had a profound impact on the distribution of plant and animal species. Many species of plants and animals were forced to adapt to the cold conditions or migrate to warmer regions. Some species, particularly those adapted to colder climates, thrived during the Ice Age, while others went extinct. Large mammals, such as mammoths (Mammuthus primigenius), mastodons (Mammut americanum), and sabre-toothed cats (Smilodon), roamed the ice-covered landscapes, and early humans, such as Neanderthals (Homo neanderthalensis) , also lived during this time. The Ice Age also had a significant influence on human history. Early humans had to adapt to the challenging environmental conditions, developing new hunting techniques, creating tools, and finding ways to survive in harsh landscapes. As the climate changed and the ice sheets retreated, human populations migrated and settled in different areas, shaping the development of human civilization. The end of the Ice Age was marked by a warming trend that resulted in the retreat of glaciers and the eventual establishment of the modern climate patterns that we see today. The warming also led to changes in sea level, as the melting ice caused the oceans to rise, reshaping coastlines and creating new landscapes. In summary, the Ice Age was a prolonged period of cold climate characterized by the presence of glaciers and ice sheets, which had a profound impact on the Earth’s climate, geography, and ecosystems, as well as human history.