Wednesday, November 16, 2016

Big families

Gang of pelicans near the new stadium building

Q: What on earth is going on behind us? We used to have peace and quiet here!
A:  It's a white elephant. Why don't they spend the money on schools, hospitals and bird sanctuaries?

It's normally very difficult to see baby pelicans, but there may be some young ones in this group

A family of about 12 ducklings. They are huddling together here to keep warm in the cold wind
 near the river. The father stands on guard against potential predators, especially dogs.

We attended the annual Kimberley Society Lecture this week:

The lecture described several techniques which are being developed by different research teams. Previously the only techniques had been used in France, a predominantly limestone area, whereas in the Kimberley the paintings are on sandstone.

The Drysdale river is derived from erosion upstream. Erosion rates are very low. So many paintings just fall off. (1 mm per 1000 years in some places). But there are higher erosion rates in higher escarpments. In rock shelters, where paintings occur, slabs of rock fall off and can be dated before and after the fall.

Mud wasp nests and remnants can be dated from all the organic materials they contain.

Mineral accretions on rocks have quite a complicated composition. When next to a piece of art, the pigment is bleached in banded fringes. Samples of accretions can be scraped off and taken back to the lab for testing and dating.

Using all these various techniques, accurate dating goes slowly, but rock art going back to 20,000 years has been definitely established.

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