Monday, 15 April 2013

GNP per capita in U.S. dollars

GNP per capita in U.S. dollars.

Wednesday, 10 April 2013

Causes of avalanches

An avalanche is a rapid flow of snow down a slope. A sudden downhill movement of snow. It is a significant hazard to people living in, or visiting, glacial areas. A slab avalanche is the most dangerous form of movement. 

Avalanches are triggered in a starting zone from a mechanical failure in the snowpack when the forces on the snow exceed its strength.

What causes avalanches:

  • Heavy snowfall
  • Deforestation
  • Steep slopes
  • Vibrations 
  • Layering of snow - for instance where snow is already on the mountain and has turned into ice, and then fresh snow falls on top which can easily slide down
  • The wind direction 

Friday, 5 April 2013

Boulder clay

Boulder clay is a deposit of clay, and contains often more boulders. Boulder clay is formed in and beneath glaciers and ice-sheets wherever they are found. The clay is scraped from the top layer of older rock by the movement of an ice sheet. An ice sheet pushes rocks, boulders and everything else in its path, which in turn wears the rock into silt-like grain.