Calcareous rocks, like limestone and marble (a rock modified by heat and pressure), are made mainly by calcite, a mineral form of the calcium carbonate. The calcite is insoluble in pure water, but the rain water contains carbon dioxide, coming from air or soil, and forms a weak acid that react with the calcite, resul... |
14 January 2008
11:35 GMT |
 |
|
There are over 200 species of plants linked to the existence of underground ore deposits. Plants usually need in low amounts metals for their metabolism. If there is too high the amount encountered in the soil, the plants depose the absorbed excess in their tissues. Sometimes, the deposits can be so big, that when th... |
21 November 2007
10:06 GMT |
|
|
In Central Australia, at the eastern edge of the Gibson Desert, there is a sandstone horst, Ayers Rock, appreciated to be "the world's largest rock", rising 348 m (1,142 ft) over the desert plateau (its maximum height is of 863 m (2,831 ft)), with a circumference of 9.4 km (5.8 mi). This is what erosion left fro... |
15 June 2007
15:16 GMT |
|
|
The common theory says that the Egyptian pyramids were made of carved giant limestone blocks that were carried up on ramps. But this explanation leaves a large quantity of unsolved questions. Two decades ago, Joseph Davidovits, Director of the Geopolymer Institute in St. Quentin, France, said that the pyramid blocks ... |
19 May 2007
08:06 GMT |
|
|
