HOW DO WE KNOW THAT ICE ONCE COVERED AN AREA?
|
A study of rocks found in an area reveals much about its past. The debris and way that sediments have been changed and distorted gives evidence of ice covering that area. Also, land eroded by ice shows certain typical landforms such as glaciated valleys with cirques, arêtes and horns. All these indicate the presence of ice sometime in the past. |
Sea ice may have covered the Earth's surface all the way to the equator hundreds of millions of years ago, a new study finds, adding more evidence to the theory that a "snowball Earth" once existed.
The finding, detailed in the March 5 issue of the journal Science, also has implications for the survival and evolution of life on Earth through this bitter ice age.
Geologists found evidence that tropical areas were once covered by glaciers by examining ancient tropical rocks that are now found in remote northwestern Canada. These rocks have moved because the Earth's surfaces, and the rocks on it, are in constant motion, pushed around by the roiling currents of the planet's interior, a process called plate tectonics.
Credit: Live Science
Picture Credit: Google