Daily Archives: April 25, 2008

Sedimentary Processes and Rocks

Posted on April 25, 2008 by

Sedimentary rocks form by the breakdown (both physical and chemical) of pre-existing rocks (these may be of igneous, metamorphic or sedimentary origin). The main factors that control this breakdown are: climate topography vegetation properties (physical and chemical) of the rock. … Continue reading →

Posted in earth, interior of the Earth, rocks | 4 Comments

Classification of Igneous Rocks

Posted on April 25, 2008 by

Igneous rocks are classified by using grainsize, silica content, and/or silica saturation. Other methods of classification include the International Union of Geological Sciences (IUGS) scheme and the Total Alkalies vs Silica scheme. Grain Size Based on the predominant grainsize that … Continue reading →

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Limestone Topography

Posted on April 25, 2008 by

Limestone caves Caves form in limestone (calcium carbonate), and occasionally in dolomite (calcium magnesium carbonate), when water containing dissolved carbon dioxide (carbonic acid) seeps into rock crevices and joints. The carbon dioxide comes from decaying organic matter in soil, and … Continue reading →

Posted in interior of the Earth | 3 Comments

Limestone Caves

Posted on April 25, 2008 by

Limestone has a peculiar quality in that whilst pure water cannot dissolve it rain water can because it has picked up carbon dioxide from the air and soil and turns the limestone into calcium bicarbonate. That process of dissolving becomes … Continue reading →

Posted in interior of the Earth, Landforms | 3 Comments