Monday, January 18, 2010
You will die — and it will all be over. You will die and find out everything — or cease asking.
I am so very, very busy today, so my apologies for the delay. This photo was taken at Fossil Bluff in Wynyard, one of the most important geological monuments of Tasmania.
East and west of the beach and at intervals for many kilometres to the east is a low flat gray rock known as the Wynyard Tillite, which is about 280 million years old and having been formed in the age of glaciations while Australia was part of the super continent called Gondwana. The glaciers flowed from the south towards the north and when they were melting and reached areas of depression they slowed down, and dropped the rocks they were carrying. Over time, mud covered the rocks, which became a mudstone conglomerate. You can find granites, cherts, quartz, jaspers and agates in the tillite, and on the beach as small pebbles.
Just behind where I took this photo is a sandstone Bluff, with layers of fossils encased in the stone. You can see the sandstone here. This Bluff was beneath the sea in the Oligocene geological period (about 38 million years ago), and it lies on top of the tillite. As you walk around the Bluff (at low tide) you are able to see where the sandstone and tillite meet. Some of the layers of sandstone are rich in fossils, showing the different climatic conditions that occurred during the millions of years of the Oligocene period.