Augrabies - Heading into the desert that isn't a desert

gavvet (78)in #geology • 7 years ago

In the Augrabies Falls parking lot is a large chunk of rose quartz. It comes from the pegmatites of the surrounding desert.

It is massive, weighs a couple of tonnes, but has beautiful color.

Rose quartz is plain old regular quartz, that has trace amounts of titanium, iron, or manganese.

The presence of these trace elements slightly alters the way light interacts with the internal crystalline structure, causing some of the red spectrum to be absorbed and thereby producing the pink color.

Heading into the desert you can see these pegmatites as piles of quartz ruble forming slight humps and low hills off into the distance. Behind this one is a fossil dune of reddish sand, with the last mountain range in the distance.

This is not a true desert as there are times of the year that rain does fall and then the sparse dry vegetation rapidly springs to life. Goats, sheep and wildlife are farmed here.

Everywhere are scattered fossil dunes.

They are fossils from a drier time. They no longer creep significantly and are frozen in time with vegetation growing on them. The vegetation acts as a wind break and further impedes what little movement they have left in them.