Geology cpr essay Example | Topics and Well Written Essays - 500 words

Geology cpr - Essay Example The banded iron deposited in these areas are said to have the biggest economic values and hence mining is quite economical, (Kesler, Stephen 443) During the formation of the banded iron, the earth was covered with acidic medium that to a large extent facilitated the formation of the banded iron. In addition, the great oxygenation that took place facilitated the formation of the hard mineral. This oxygen was fixated by primitive microorganisms that existed during the formation. Photosynthetic bacteria were largely attributed to the formation of banded iron. These bacteria synthesized their food in chemical processes that released oxygen gas. It is important to note that iron is highly reactive with oxygen and hence, it readily formed iron oxide that settled at the bottom of ancient oceans, (Kesler, Stephen 473). This is the most relevant theory that explains the large existence of iron oxide in several iron ores. Before the formation of the banded iron, oxygen gas did not exist, (Trendall 1). The gas only became existence as result of chemical reactions in the photosynthetic bacteria. Geologists agree that as the cyanobacteria became numerous in the earth, the oxygen emanating from the photosynthesis accumulated in the atmosphere and hence that is the reason why we have the precious oxygen. In the earth’s ocean, dissolved iron combined with oxygen forming insoluble oxides of iron. The iron oxides then precipitated out leading to a formation of a thin coat on the ocean floor. The thin layer formed into cherts and shale resulting into a complete cover all over the ocean floor. This brought about the stratification of the oceans and hence the ocean waters is "stratified" Over millions of years ago, iron oxide and silica were precipitated repeatedly over a long period. This resulted in the deposition of alternating layers of hematite (which is red),