Natural Distribution and Abundance of Elements

Abstract

A widely recognized biological characteristic of a healthy and sustainable environment is diversity—as with biology, so with geology. Regions characterized by the presence of different bedrock units, and different surficial materials in areas affected by recent (geologically speaking) glaciation, develop varied landscapes that support differing ecosystems. Examples of varied landscapes range from Alpine and Cordilleran mountains, through gentler landscapes of rolling hills, to the glacial plains of Northern Europe and North America, or similarly from the high Himalayas, through verdant foothills, across fertile plains to the desert of Sind. In the parts of the world characterized by stable geological platforms, where mountain building has not taken place for many hundreds of millions of years and there have been long periods of landscape development, peneplains are the eventual outcome. Their topography is gentle without mountains. High relief areas are largely limited to inselbergs or ravines and river valleys where, due to crustal uplift, modern rivers and streams are cutting down into and eroding the old land surfaces. Examples are the Brasilian Shield, central Australia and parts of central Africa, though in the latter young volcanoes lead to local mountainous terrain. These are the physical expressions of the underlying geology, but there is another changing characteristic that cannot be seen directly—the chemistry of the underlying rocks and sediments and the soils that lie upon them.