Hiking Suikerboschfontein - Part 17 - Tidal varves indicative of Marine deposition

As one descends into the gullies you pass through the hard quartzite cap into the shales.

Sand is deposited in shallow water and shale is the mud that is deposited in deeper water.

Since this mud was deposited just below the sand layers the water was deep enough for mud to settle but shallow enough to be influenced by tides

The movement of the tides in and out results in different rates of mud deposition and this is preserved in the rocks as alternating horizontal bands seen below.

More tidal banding.

Seasonal varves are also found in ice, representing winter snowfall(light) and summer melt(darker blue) and in trees.

In trees the thicker part is rapid summer growth and the thinner harder ring represents retarded winter growth.

Just as tree ring can be counted to estimate a trees age. Ice layers reveal secrets about past climates and tidal varves in rocks can reveal facts, like how many days there were in a year, in the very distant past.

To be continued...