Progress

If time will allow the following blogs will be following but apologies if time doesn't allow as it is a very busy period for myself at the minute!!

• Glaciers in the UK
• Glaciers as a resource - tourism
• Living with Glaciers - farming and conservation.

Ciao for now x

Himalayan Glaciers

Aim: To be able to understand how and why glaciers prove useful to humans.

Glaciers are useful for a variety of reasons including; 

• Glacial Meltwater - especially for the Himalayas - this meltwater can provide the water supply to many, including those previously threatened in Asia. Half of the worlds population live here and below states why glaciers are important otherwise the region will be at risk 

• REGIONS AT RISK CASE STUDY: HIMALAYAN GLACIERS (WWF NEPAL PROGRAMME 2005)
  
  
  FACTS:
• Retreat since 1850.

• Feed seven of Asia’s great rivers: Ganga, Indus, Brahmaputra, Salween, Mekong, Yangtze and Huang He.

• Ensure a year round water supply to billions of people.

• Since mid 1970s the average air temperature in the Himalayan region rose by 1°C.

• New Scientist article “Flooded Out – Retreating Glaciers Spell Disaster for Valley Communities” 5^th June 1999 quoted Professor Syed Hasnain “most of the glaciers in the Himalayan region will vanish within 40 years as a result of global warming” and freshwater flow in rivers across South Asia will diminish and create shortages.

• Khumbu Glacier: a popular climbing route to the summit of Mt Everest has retreated over 5km since Sir Edmund Hillary and Tenzing Norgay set out to conquer the world’s highest mountain in 1953.

EFFECTS:

• FRESHWATER: Low flow contribution of Himalayan rivers during the dry season is from snow and glaciers melt. The runoff supplies communities with water for drinking, irrigation and industry and vital for river and riparian habitats. The accelerated melting of glaciers will cause an increase in river levels, leading to floods and landslides.

• HAZARDS: Frequency of Glacial Lake Outburst Floods will increase, costing lives, property and infrastructure. 1988 – outburst of Tam Pokhari in Nepal killed two, destroyed more than six bridges and washed away arable land. Loss worth over 150 million rupees (£1 300 000)

•  ECONOMIC: The implications for industry extend beyond ‘energy’: chemical, steel, paper and mining industries that rely directly on river/stream water supply would be seriously affected. Reduced irrigation would lower crop production which would lower available food and thus malnutrition.

 Figure 2: Map illustrating the location of the Himalayas (Qwickstep,2010)

Figure 3: Image illustrating a Himalayan glacier (Hoffman, 2009) 

Glaciers - a hazard? The Case of Lake Missoula

 Aim: To be able to understand when glaciers become a hazard, by focusing on the case of Lake Missoula.


Throughout the Earth's life the climate has fluctuated to temperatures even colder than today. This change in temperature can last for 2-10 million years and this is known as an ice age. There have been at least 5 major ice ages in the past and in the most recent advance the amount of glacial cover had reached its maximum cover and had almost all melted by 10 000 years. It was during this advance that the finger from the ice sheet moved southwards through the Purcell Trench, damning the Clark Fork river - therefore creating Lake Missoula.( See figure 1)

Figure 1: Map illustrating the location of Lake Missoula and the flood path it took (Source: Reference)

Soon the water started the build up behind the 2500 ft ice dam filled the valleys to the east creating a glacial lake the size of Lake Erie and Lake Ontario combined! The water continued to rise to 4200 ft, putting immense pressure against the dam until that castastrophic day when the dam could take no more pressure.


The ice failure gave way and released the volume of the Irish sea in glacial water in a shock wave tearing through the continent in 48 hours - destroying everything in its path. Making it was one of the largest floods in the history of the planet. The rate of flow of the water was SIXTY times that of the amazon and at 60mph and 100m high it cut 200m deep into the land. It took 10 hours for the flood full of debris to travel from the source to the ocean (the length of GB).




Look at the landscape it has left.....

Figure 1: Dry Falls, Washington (Source: Reference)

Figure 2: Frenchman Coulee, Washington (Source:Reference)

 

Morraines

Aim: To be able to understand the concept of a Moraine.

Once glacial ice has melted, a variety of rocks are laid down that have been carried down by the glacier. Piles of this material is named Moraines. They are usually seen as lines, or a series of mounds running across glacial valleys.

There are many types of moraines (See figure 1) ; the main types are terminal or end moraine which are found at the snout of the glacier.

Figure 1: Diagram illustrating the different types of moraines. (Source: Reference)

Terminal Moraines:

• Consist of a material ridge stretching across a glacial valley
• they are elongated at right angles to the direction of the ice advance
• often steep sided and can reach heights of 50-60m
• often crescent shaped, moulded to the form of the snout
• formed from unsorted ablation material when the ice melts and the carried material has been deposited (Therefore they contain a variety of material)

As a glacier retreats, a series of moraines may be formed along the glacial valley, marking points where the retreat may have paused. (Recessional Moraines)


When the climate cools down, a glacial advance will occur and the previously deposited moraine may be shunted up into a mound known as a push moraine. 




Now test your knowledge with a quick quiz!! 


Quiz

Drumlins

Aim: To be able to understand what the term drumlin means.


The term drumlin is originally derived from the Gaelic word of druim. This takes the meaning of a rounded hill (See figure 1). They are usually known as elongated hills of glacial deposits.They can stretch from anything from 500m to 1km in length - normally in the direction that the glacier was going, and it is not unusual to see more than one in the same area.A group of drumlins is named a drumlin swarm or more commonly known as a swarm of eggs.

Figure 1: Diagram illustrating a typical drumlin (Source:Reference)

Other main features of a drumlin include:

• smooth, oval shaped small hills, often resembling the top half of an egg
• can be up to 50-60m in height
• steep end known as a stoss and a gentle sloping end (lee)
• they are enlongated in the direct of the glacial flow with the steep end at the upstream end and the lee at the downstream
• they are formed form unsorted till
• they are found on lowland plains such as the Ribble valley (Figure 2)

Figure 2: An example of a drumlin from the Ribble Valley (Source:Reference)

Glacial Transportation and Deposition

Aim: To be able to understand the way Glaciers are able to transport material and then deposit it further along.

A glacier can not only shape valleys and create fjords, a valley glacier is also capable of transporting a variety of material - all things great and small ! Some of this debris may be derived from previous rockfalls from the valley and the surrounding area. This is then transported on the surface of the glacier which is named supraglacial debris. Otherwise the debris may be buried within the glacial ice - named englacial. 

Figure 1: Image illustrating some of the debris carried by glaciers (Source:Reference)

Subglacial is the material found at the base of a glacier, which may include fragments of rock and eroded material at the base of the glacier. Another term for describing this type of debris is a more popular noun of Moraine. (See figure 2)

Figure 2: Diagram illustrating a glacier in terms of debris and moraine (Source: Reference)

The large amounts of debris that is transported by a glacier is eventually deposited further along the path. The majority of this will be the material released by the melting of the ice at the glacier snout or where the glacier changes between compressing and extending flow. The debris that is directly deposited by the glacier ice is known as boulder clay or till. (See figure 3)

Figure 3: Diagram illustrating where the boulder clay is layed down (Source:Reference)

Till: This is an unsorted mixture of rocks, clays and sands that has been transported as supraglacial or englacial debris and deposited when the ice melted. The stones tend to be angular or in some cases sub-angular (unlike river and beach material which is smooth and round). Till can sometimes be transported across the country - for example some from south Lancashire has be sfound in the Lake District and souther scotland. 

Sometimes a large boulder that has been moved from one area and deposited in another which has a very different geology is known as erratic.

Types of glacial deposit:

Lodgement till - subglacial material that was deposited by the moving glacier. (A drumlin is a typical feature of this).

Ablation till - is formed at the snout of the glacier where the ice has melted. Terminal end, push and recessional moraines are typical features.

Glacial Troughs....and the rest !

Aim: To be able to understand what a glacial trough is and their major features.

Whilst glaciers flow down pre existing river valleys in upland areas, they widen, straighten and deepen these valleys through the processes of glacial erosion previously discussed. V shaped valleys are turned into U shaped valleys (see figure 1) due to the action of the ice, cpombined with large amounts of meltwater and sub-glacial debris, create large erosion rates than that of the river water. 

Figure 1: Image illustrating a U shaped river valley, shaped by glacier erosion. (Source: Reference)

Extending and compressing flows are acting upon the valley creating a variety of erosional rates. Compressing flows creates the valley floor to over deepen, which leads to the formation of rock basins.

Figure 2: Maybe not this type of rock basin !! See if you can find an image of a real glacier rock basin.

Major features of glacial troughs:

• Fairly straight with a wide base and steep sides – hence the U shape.
• Stepped long-profile with alternating steps and rock basins
• Glacial valleys can end abruptly at their heads in a steep wall. This is known as a trough end (Figure 3)
• Rock basins filled with ribbons lakes (Case study – Wastwater in the Lake District)
• Over deepening below the present sea level – this has led to formation of fjords when sea levels rose after the ice ages and submerges the lower parts of glacial valleys. (For example the coasts of Norway – where people going on a fjord cruise!) (Figure 4)
• Hanging Valleys are located on the side of the main glacial valley. These are either pre existing tributing river valleys which were never glaciated.
• Areas of land known as spurs, projecting from the river valley side have been removed by the glacier, producing truncated spurs. (Figure 5)
• Roches Moutonnees are left when small areas of rock on the valley floor are not always removed. The top is polished by the process of abrasion and the downstream side is made jagged by the process of plucking.
• Shallow lakes are created once ice has melted and filled glacial troughs. Their sides were modified by frost shattering and the development of scree which altered the glacial U shape valley.

Figure 3: Image illustrating the formation of a trough end(Source: Reference)

Figure 4: Image showing a fjord cruise (Source:Reference)

                            

Figure 5: Image showing an example of a truncated spur (Source:Reference)

Glacial Erosional Landforms - Corrie

Aim: To be able to understand glacial erosional landforms

Glaciers create unique landforms in upland areas, just look at some of Scotland’s most beautiful scenes in the clip below near Loch Lomond. Take particular note of the before and after glaciations landscapes.

 Video describing the effects of glaciers on the Loch Lomond area. (Source:The video)

Figure 1: Image illustrating Loch Lomond (Source:Reference)

One example of a glacial landform is a Corrie.

Figure 2: Diagram illustrating the formaton of a Corrie (Source:Reference)

 A corrie is an amphitheatre shaped rock hollow and has a steep back wall with a deepened basin. It is often associated with having a small lake known as a tarn. For example the one seen in the photograph below at Low Water Coniston Old Man in Cumbria. 

Figure 3: Image illustratung a tarn in a corrie in Cumbria (Source: Reference)

Corries in the UK are normally found on north or north east facing slopes due to their isolation allowing more accumulation of snow. If there is more than one corrie lying back to back or alongside each other, a process of enlargement normally occurs. This leaves a narrow, steep sided ridge between too hollows. This is called an Arête (See example below). Examples of Arêtes can be found on Helvellyn in the Lake District – see if you can find out more information about it and provide a case study!

 Figure 4: An example of the formation of an Arete. (Source: Reference)

 

 

When two or more corries develop on a mountain, the central mass will still stand and be known as a pyramidal peak. It normally has a sharp appearance die to frost shattering and an example of one of these is Matterhorn in the Alps (See photo below).

Figure 5: Image illustrating the Matterhorn in the Alps (Source: Reference )

The formation of Corries:

• The original process is named nivation, this acts upon a shallow and Periglacial hollow and enlarges it into an embryo corrie. This can take a low amount of glacial time – so a very very very very long time within an ice age).
• As the hollow grows, more snow is added and the weight causes it to compress and forms firn and eventually ice.
• As time goes on the process of plucking will erode away at the back wall to create a steeper drop and the rotational movement of the ice, in addition to the debris created by plucking erodes away the floor of the hollow.
• This overall will deepen the corrie. As this deepends, the ice at the edge (which is thinner) does not produce the same amount of down cutting and so therefore a rock lip will develop at the boundary. Some of these will have their height increased by morainic deposits formed when the snout of the glacier was in that position.
• Once all of the ice has melted, the corrie fills with meltwater and rainwater to form a small lake, formerly known as a tarn.

CASE STUDY: The perfect corrie to investigate is Helvellyn in the Lake District. Why not try to find out as much information as you can about this corrie to be discussed as a class next time to form a solid case study from all resources.