ScienceAnd Blog

Adaptation to atmospheric pressure, temperature and chemistry

Minerals are adapted to their environment just as are organism.  In lava flows the minerals in the rock were formed at high temperatures, moderate pressures, and a chemical environment that lacked much oxygen and water.  When the lavas are extruded at the surface the minerals are in a new chemical and physical environment.  The selection pressure is higher on some minerals than others. Quartz tends to respond very slowly forming sand grains but the other minerals, particularly feldspars are quite unstable.  The chemical lattice adapts to the new environment of low pressure, low temperature, and high O and H₂O by forming clay minerals.  Clay minerals and sand with the addition of organic debris form soils, and soils allow vegetation to grow.  The photo sequence shows my former colleague [Tony Brink] standing on older and older lava flows in central Africa.  The vegetation density can be seen by using Tony for size comparison. Photographs courtesy of the late Tony Brink, University of the Witwatersrand.

Photo-series 1

The effects of a changing chemical environment

A normal pristine swamp in southern Louisiana before and after blockage of drainage and the intrusion of salt brine due to drilling operations.  The effect is essentially immediate and within half a generation [15 years] no trees will remain standing unless drainage is unblocked and fresh water allowed back into the area.

Photo-series 2

Classical predator adaptation

The classical predator selection pressure case involving the British Pepper Moth.  Source unknown: pre-1965 teaching photo archive.

Photo-series 3