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Case Studies
The Guide includes fourteen Case Studies:
On Good Friday 1964, Alaska was struck by a magnitude 9.2 earthquake which caused severe damage even in this relatively unpopulated State. A series of tsunamis killed people not only in Alsaka, but also twelve others as far away as California. The photograph shows a ship carried some way inland by the tsunami. |
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The River Nile has, from the dawn of civilisation, brought life to the people of Egypt. It not only supplies water to this desert country, making a fertile strip of land alongside the river, but its annual flood waters spread silt - new soil - across the farm land. Unfortunately, the dry season brought drought. In order to regulate the flow of the river, a dam was built in 1902 at Aswan. A new, much larger dam was completed in 1970 - the Aswan High Dam. The dams also provide water for hydro-electric power stations. But there are problems too when dams interrupt the normal cycles of a river ... ... The photograph shows the temples of Abu Simbel, re-located above the new level of Lake Nassar.
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- Channel Tunnel
- easy to bore through;
- consistent and uniform;
- permeable;
- strong.
Since 1800, engineers have dreamed of digging a tunnel between England and France.
The dream was finally realised in 1994 with the opening of three 50-km long tunnels, including the longest undersea section in the world.
Tunnelling underseas presents its own problems. If possible, the rock must be
Chalk forms prominent cliffs around the coasts of southern and eastern England. These vertical cliffs show that chalk is soft enough to be eroded easily. Marine erosion at the base of the cliff causes landslips. Chalk shows many examples of instability. |
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Chalk is a porous, permeable, fractured rock which underlies much of south-eastern England and provides much of south-eastern England with water. Use the map to identify the areas of the Chalk (in green) which are confined, and which are unconfined, aquifers.
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- Mining for Metal Ores
There are mines all over the world. But some are bigger than others.
Kiruna (left) is the largest deep iron ore mine in the world.
Bingham Canyon (right) is the largest open cast copper mine in the world.
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- Mount St Helens
On May 18, 1980, after weeks of warnings, the side of Mount St Helens collapsed and erupted one of the largest lateral blasts in recorded history, sending pyroclastic flows and lahars across the surrounding countryside, and flattening trees up to 30 km away.
The volcano was being monitored and an exclusion zone had been set up. Some people ignored the warnings; 57 were killed.
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Mount Pinatubo in the Phillipines was a closely monitored volcano. So, its eruption of June 1991 was accurately predicted and thousands of people were evacuated or accommodated in shelters. The death toll was kept below 300. Any monitoring is expensive in time and equipment. This operation cost $55 million. Was it worth the high cost? |
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In Northern Ireland, the Chalk is overlain by Tertiary plateau basalts. The Chalk is relatively weak and the basalt is rigid and heavy, a recipe for landslips, encouraged by the melting Irish Sea glaciers which removing support from the cliffs at the end of the Ice Age. |
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There are many places in the world which have more extensive examples of columnar jointing in basalt lavas. The Giant's Causeway, however, is nearer to home, easily accessible and visited by up to half a million visitors a year. |
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The landslip at Mam Tor, Derbyshire, is the largest of about 600 landslips in the county. Over the past 50 years, the main road which climbs along the side of the hill has fought a losing battle with the landslip. The landslip is marked by the prominent scar in the side of Mam Tor. |
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It took about 50 years for the Theory of Plate Tectonics to reach fruition. Original ideas were hampered by lack of the appropriate Physics, but as new research widened the possibilities, the Theory became a major unifying force in modern Geology. This Short History summarises the main steps in the development of this complex theory. |
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The Troodos mountains, which lie across the heart of Cyprus, show a section of former oceanic crust and underlying mantle – an ophiolite suite. 100 million years ago, these layered gabbros, sheeted dykes and pillow lavas were forming new oceanic crust at a spreading plate margin. Since then, as the African plate collided with the Eurasian plate, Cyprus has been raised above sea level, leaving a large section sea floor and oceanic crust for us to study very conveniently on dry land. |
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On 11 March 2011, the east coast of Japan was struck by the strongest earthquake in its recorded history, followed by a devastating tsunami which killed at least 11,000 people. This case study describes the catastrophic event and puts it in its geological context of a subduction zone of a destructive plate margin. |
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