Dalradian Limestone

Schiehallion Limestone Pavement 

Limestone Pavement

Limestone Pavement


The Dalradian Limestone is 600 million years old, much older than the Carboniferous Limestone that makes up the Pennines and the Burren in Ireland. It is unusual in that it does not contain fossils and was produced by precipitation on the sea bed. It has passed through the Caledonian orogeny (mountain building process) and so has been hardened but is not quite a marble. There are bands of mica within it and when it weathers it crumbles into sugar-like grains.
In the Rannoch area it occurs as Limestone pavements and produces potholes, dolines, caves and swallow holes. In places drinking water is hard because of calcium in the water. Like other limestones it is dissolved slowly by acid water and it is this that has given the features listed above. The Schiehallion Limestone Pavement is a Site of Special Scientific Interest (SSSI) and is probably the best example of a Dalradian Limestone Pavement in Scotland. Many plants like lime conditions and flourish on the Dalradian Limestone. Examples include Rock Rose, Globe Flower, Thyme, Astragalus, Northern Felwort and Wild Strawberry. The grooves that are dissolved in the Pavement are called grykes and may be very deep - perhaps six feet deep. The higher areas between grykes are called clints. The calcium carbonate which is the dominant mineral in the Limestone is in the form of calcite although when it gets incorporated into shells such as the snail Sepia nemoralis it is converted into Aragonite. Snails are common where there is Limestone, as is a white lichen which grows on the rock.
The grykes provide protection from grazing for various woodland flowers such as Dog's Mercury, Herb Robert, Herb Bennet, Wood Anemones, Wood Sorrel and Ivy as well as small Birch and Rowan trees.

Schiehallion Limestone Pavement

The Schiehallion Limestone Pavement showing the characteristic grykes and clints as well as white lichen.

Schiehallion Limestone Pavement

Ivy growing in the grykes

Ivy growing in a gryke.

Ivy growing in a gryke

Ivy growing in a gryke.

Biotite Schist Erratic

Biotite Schist Erratic with honeycomb weathering. The honeycomb weathering is produced when the iron in the rock is differentially weathered more rapidly than other minerals leaving a pock-marked effect.

At Braes of Foss there are some small potholes and a swallow hole where the small burn disappears below ground to reappear on th other side of the road. In places the ground has collapsed (dolines) because the limestone beneath has been dissolved away.
On the south side of Schiehallion is the Giant's Cave which is actually a relatively small Limestone cave.
At Lassintulloch there are further potholes on the flanks of Schiehallion.
At Trinafour there is a small Limestone Pavement and another swallow hole.


Subpages (1): Lime loving flowers
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