Ice Erosion Summary Report cont.

Human society can benefit from understanding landforms many times over, from reasons as pragmatic yet vitally necessary as farming in optimal conditions and knowing what crops will grow best in, to avoiding the dangers that they can pose such as the catastrophic collapse of many a glacial lake, to efforts in combating climate change by being proactive and working to reverse damage done instead of a quick fix, to appreciating these areas and their culture.

Understanding brings respect and proper care. Ice, while not the fastest or most common agent of erosion, is indubitably the most powerful out of other major causes such as water and wind. Ice can change the world. It can span continents, raze hillsides to soil and create the most majestic landforms seen anywhere on Earth. It can also change our lives, our ways of thinking, our attitudes and ideas; all of this from just understanding. Ice as an agent of erosion and inspirer of change truly is a force to be reckoned with.

Glacial Lakes

These lakes began life as large pools of glacial meltwater, and have been supplemented with rivers and rain since. At the end of the Last Glacial Maximum, glaciers began to recede in response to warming temperatures. Significant deposits of ice were left behind in the hollows of hills, which then melted and formed lakes. Glacial lakes are often accompanied by other signs of glacial activity, scoured valleys, deep striations in bedrock and other landforms which make up the surrounding landscape.

Glaciers grind rock that they flow over, turning them into sediments which form the bottom of the lake. On occasion, the result is so fine and silt-like that it is called glacial flour. When it becomes suspended within the water, it gives it a unique, sometimes milky colour along with a greenish tinge because of the algae which thrive in such mineral-rich water. Lakes formed by ice can be told apart from those formed by water. The banks of glacial lakes are irregular and jagged, reflecting how glaciers carve out a path through land, but lakes with origins in liquid water have smooth shores and are interconnected with rivers more often.

Where the glacier has been can be told from the sediments deposited within the lake, as glaciers are capable of transporting material far from where it originally lay. As sediment varies with location, it affects the water’s mineral content. Animal activity also leaves trace elements, which then go into forming layers of sediments at the bottom metres thick. Glacial lakes can be studied in this way by analysing these layers and their chemical composition; useful details may be found on dates and manner of formation, as well as recent changes and impacts on the lake.

Further reading on the dangers glacial lakes can be:
http://www.theuiaa.org/bursting_glacial_lakes_in_nepal.html

Benefits of Understanding Landforms 4

This century has marked a renewed interest in the impact humans are having on their environment. Much new knowledge has come to light, particularly the concept of climate change and global warming. This theory on future trends of the Earth’s climate has incensed much debate, particularly the possible outcomes and results this will have on the environment. They are quite bleak, predicting that biodiversity will shrink enormously, countless irreplaceable species will become extinct, weather patterns will become irrational and violent and that Earth will not recover from its countless ills for millions of years, if at all.

Such a chilling prospect has instigated newfound activity and effort in countries across the world. Public awareness has been raised, educational campaigns on what we can all do to help have been executed and research and innovation shown by our scientists. So where can ice-related landforms help?

A cause of many of the landforms explored here is the glacier. When exposed to warmer-than-usual conditions and disrupted weather patters, ice melts. For this reason glaciers have been studied as an indicator of past trends in the Earth’s climate history, garnered knowledge then used to make predictions about the future. Ice leaves behind clear evidence of where it has been with formations and signs such as moraine and the valleys they have carved out. Dating the minerals within can provide information on periods of activity, cessation and retreat. Cycles such as these can be then analysed to produce overall directions on where glaciers have headed.

Understanding glaciers and recognising the landforms that they produce will prove invaluable in the combined effort of humanity in understanding the disaster it is headed towards and taking steps to avert it, even rectify the damage done in ignorance.

Moraine

Originally a French term, moraine is any accumulation of glacially-caused and deposited debris, mostly taking the form of sediments and soil, yet particle sizes from boulders to silt-like glacial flour can be found too. This debris is also unconsolidated, or loose. As it is caused and left behind by glaciers, moraine is useful in determining the history of glacial activity in the area even if the glaciers themselves have long receded and disappeared.

Several types of moraine exist, classified by their dimensions, method of formation and where they lay in relation to the glacier. The glacier may cause debris to drop from pre-existing stone, grind it from the rock it flows over beneath or cause formation on its upper surface. Some examples include:

Lateral moraine forms at the edges of a glacier where cold and abrasion causes its valley walls to loosen and drop material. The glacier then crushes and grinds some of this.

Medial moraine is found in the unusual event of two glaciers merging together into a whole. The lateral moraine on the inner edge of the meeting becomes located at the centre of the new glacier. A line of this running down the centre of a valley tells of this occurring.

Englacial moraine is unique in that it can only be called englacial while its glacier still exists. It is any debris that has fallen onto the glacier's surface and become embedded within. This includes material that has fallen into cracks and crevasses.

Push or Terminal moraine appears as a ridge at the nose of a glacier, being comprised of material pushed up in front of the glacier as it advances. When a glacier retreats or becomes stationary, the moraine is left behind and so is useful in deciding the extent a glacier once had.

Benefits of Understanding Landforms 3

Hazards are present in everyday life. By understanding these dangers we can better take precautions against them and avert loss and injury. Prevention is much more efficient than the cure. Natural hazards also need to be understood. The formations that ice works upon the land are often splendid and unique, but pose a danger to anyone in the area.

Mountaineers, for example, have been swept away and killed by collapsing seracs and avalanches. Crevasses have swallowed up many a hapless hiker. And the damage that unstable glacial lakes can cause is remarkable. During one such outburst flood in Iceland, a valley was temporarily turned into the largest river second only to the Amazon in terms of volume of flow. Ice floes weighing thousands of tonnes were brought with the torrent and destroyed infrastructure and property. Even the Strait of Dover, separating the British Isles from the European mainland, was thought to have been created by a cataclysmic outburst flood.

In K2's worst mountaineering accident in history, 8 climbers out of 11 were killed by falling seracs in 2008

Programs and have been undertaken by governments to identify glacial lakes that may collapse. Any traveller in glacial regions ought to have been instructed in safety precautions and procedures associated with their situation, particularly if on an expedition. And any warning signs of geological tumult are taken seriously, with populated areas evacuated as soon as possible. Long experience has taught much, yet people still die.

Understanding landforms created by ice will give us the capacity to appreciate and respect great natural forces at work yet avoid the dangers and casualties that they may inflict. Especially if they turn out to be unnecessary and preventable.

Truncated Spurs

When a watercourse or small river meanders down a sloping gradient, it will eventually carve out a v-shaped pathway. Due to not having any clear course, the river will often wander back and forth in a zig-zag pattern. The bluffs that are made prominent by the watercourse as its path deepens often appear in a formation not unlike the teeth of a zipper. These ridges are then called interlocking spurs.

Truncated spurs are formed from interlocking spurs. When a glacier moves down the previous river’s pathway, it is unable to flow around the ridges like flowing water could; so it shears the tips off and leaves behind a wide, straight valley with extremely steep sides. Truncated means cut off or terminated, and that is what those interlocking spurs have become.

The spurs appear blunt and triangular in cross-section, and the grooves between them can be sometimes termed as hanging valleys, named so because of the sudden drop at their end. Watercourses flowing down these hanging valleys find this out when they form waterfalls, which then continue their downwards path that leads eventually out to sea.

Ice Erosion Summary Report

Moving ice erosion is an important erosion agent as it is the strongest erosion agent and places all over the world have been affected by ice erosion. When you look for different types of ice erosion, you should look for ice sheets, glaciers, continental ice caps, crevasses, seracs, cirques, comb-ridges, U-shaped valleys, hanging valleys, roches mountonnees, fiords, glacial lakes, truncated spurs, varved shale and moraines. The way most of these ice related landforms are formed mostly by glaciers. For example, U-shaped valleys are created when a glacier goes through a V-shaped valley.

Ice erosion can take in two different forms, the movement of ice or through freeze-thaw processes when water inside pores and fractures in rock may expand causing further cracking.

Glacial erosion erode in three different forms –

• Abrasion – is the mechanical scraping of a rocky surface by friction between rocks and moving particles during their transport by glaciers, wind, waves, gravity, running water or erosion. After friction, the moving particles dislodge loose and weak debris from the side of the rock.
• Plucking – also known as quarrying, plucking exploits pre-existing fractures in the bedrock. This is then followed by the entrainment of the loosened rock by the ice.
• Ice thrusting – the glacier freezes to its bed, then as it surges forward, it moves large sediments at the base along with the glacier.

Through these ways of glacial erosion, things like moraines, ground moraine, kames, kame delta, drumlins and glacial erratics.