Ben Alder Cottage

The building blocks of Ben Alder Cottage

The rock that underlies Rannoch Moor is Granodiorite (like granite but with some mineral differences). It was intruded into the roots of the mountains produced by the Caledonian Orogeny (mountain building process). The Caledonian orogeny occurred between 490 and 390 million years ago when continents, carried on the Earth’s tectonic plates, collided and folded up their edges. Since then the huge mountains (as high as the Himalayas) have eroded away to expose the roots which are the Scottish mountains that we see today. Because the molten magma cooled slowly in the roots of the mountains it had time to grow large crystals which is what characterises Granodiorite- large black and white crystals. While the magma was molten it came into contact with the existing rocks and bits of them fell into the magma and were engulfed but retained their identity- these are called Xenoliths. The word means stranger rock. (Greek, Xenos - Stranger and Greek, Lithos - Stone). Lithology is the study of rocks.

Then along came man and decided to build Ben Alder Cottage and so we see cross-sections of the rocks in the walls of Ben Alder Cottage. Even later, along came man and photographed them and posted the photographs on Facebook with a longwinded and rambling explanation.