Monday 17 September 2012

Ice-Age Ardnamurchan - 1

This picture of the 'snout' of a glacier in the Canadian Rockies gives some idea of what West Ardnamurchan may have looked like some 10,000 years ago when the last Ice Age was coming to an end.  As in the Rockies, the glaciers that covered the area were melting back having, at one time, buried the land so deeply that not even the highest peaks were protruding above the ice.

As glaciers retreat they leave a mixture of debris varying in size from clay and finely powdered rock to huge boulders weighing tens of tons, material they picked up as they ground down their valleys, or which fell onto them from surrounding mountains.  While the streams that began to work the newly-exposed land quickly removed the finer particles, the larger boulders were left behind.

Rocks and boulders carried by the ice show signs of rounding.  After the ice had gone, but while the landscape remained bitterly cold, freeze-thaw effects dislodged further rock from the steeper hillsides and oeaks, sending it tumbling down into the old glacial valleys.

This sort of rubble still strews the slopes of many Ardnamurchan hills, much of it half-buried in the soils and vegetation which have grown since.  But much of the rock material which once covered lower ground has either been covered by a soil profile, with thick peat profiles developing during a wet period some 4,500 years ago, or it has been removed for use by man.

Glacial rock debris is the most wonderful material, lying around a landscape ready to be put to use.  In an area where this raw material is so plentiful, we should spare a thought for lowland communities which have had to use much more temporary materials such as wood and clay.

So, over the six thousand years that man has been farming this area, thousands of tons of glacially-derived rock have gone into building houses, byres, walls, fanks, tombs, duns, castles, forts, cairns, roads, monuments and public buildings.  It's been used for grinding grain, as ballast in boats, as weights for fishing lines, in fish-traps, in hunting, and for killing each other and covering dead bodies.

Bottom photo shows the field walls and houses of the abandoned village of Glendrian.

1 comment:

  1. Having just returned home after my time on the Ardnamurchen peninsula, I found this fascinating. Thank you!

    ReplyDelete