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Geology
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- Geology 1
The Rosneath Peninsula contains a number of outstanding geological features. The best known of these is the highland boundary fault which runs straight as a die across to the east coast at Stonehaven. On the peninsula, the fault can be clearly traced as a depression running across the spine, serving as a natural route for the main road connecting the village of Rosneath on the Gareloch side to Kilcreggan on the Loch Long side. To the north of the fault are the Dalriadan rocks, upwards of 500 million years old, and to the south is found the 350 - 400 million years old formation known as the old red sandstone. Hence, technically at least, part of the peninsula is in the Highlands, part in the Lowlands. Generally speaking, the best soils for cultivation are found on the sandstone. In consequence, the main arable lands occur on the south side, grazing land and forestry plantation predominate to the north.
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- Geology 2
The Dalriadan rocks tend to be more resistant to erosion than the sandstones, and although the peninsula as a whole forms fairly low and rolling hills, further to the north and west high more rugged land is found, giving real character to the region.
Many of the landscape features were formed at the time of the ice age. Great glaciers marched down from the high ground to the north, occupying the troughs now occupied by the Gareloch and Loch Long - Rhu Spit represents the terminal point of the Gareloch glacier, where rocks and silt were deposited as the ice melted. Ice action also helped to smooth the hills of the peninsula to the form that we see today.
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- Geology 3
When the ice finally melted about 9,000 - 10,000 years ago, sea levels rose quickly. However, as time went on, the land, now relieved of the great weight of ice, slowly rose relative to sea level. The result is that in many parts of the peninsula, old sea cliffs and raised beaches can be found. Indeed, the main road round the coast and the houses adjoining have been helped considerably by the existence of the platform provided by the old beach.
Another feature of the ice age was the deposition of boulders, brought in from other areas, and dumped down where and when the ice melted. Often these boulders, known as "erratics", are partially rounded through scraping against other rocks. The well-known painted rock on the shore at Kilcreggan, "King Tut", is one such.
Photographs
1.© Sea Pigeon http://www.flickr.com/photos/seapigeon/322562708/
2.© John McLeish, Clarkston http://www.ianmcleish.fotopic.net
