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Sunday, 13 February 2011

Uiskentuie strand

As you drive along the Uiskentuie Strand there is a steeply sloping, and in places scrub-covered, bank on the inland side. This is often (and wrongly) referred to as a raised beach. It is in fact the outwash from a glacier, a mass of stones and sand deposited by a river that flowed out of a glacier that once extended over this area. As the glacier retreated, it left all this behind. If you climb up the bank, you will see that it is up to 300 metres wide at the western end, with run-rig and old peat diggings on the top.
With the melting of the ice (once a kilometre or more thick), the sea-level rose as much as 30 metres, flowing over the bank (the trig point on it stands at 29 metres) and then gradually eroding it into the present-day steep slope as the sea-level fell. The final act of the sea, some 6,000 years ago, was to deposit a series of four gravel ridges close to the foot of the bank. There was once (1920s to 1930s and perhaps earlier) a nine-hole golf course on the ground between the bank and the road here. Even today, one occasionally sees a golfer practising his swing and knocking balls about, while passing motorists keep a very wary eye open for them!
Much of the above came from the booklet 'A Guide to the Geology of Islay' by Alex Maltman and others. Available to purchase at the INHT Centre.

Malcolm


Uiskentuie Strand with eroded bank of glacial outwash

The top of the bank showing run-rig and, in the distance, old peat diggings
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2 comments:

  1. Anonymous14 February 2011 at 15:14

    Rather than sea level falling, the land rose. Subsequent to the sea level rise at the end of the ice age, the land rose, through isostacy, and the raised beach on which the road runs, was revealed.

    So on the east side of the road we have a beach, and on the west side of the road we have a raised beach.

    I therefore will continue to refer to this as a raised beach.

    Iain M Campbell

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  2. Anonymous14 February 2011 at 15:51

    Actually, there isn't a lot of difference in the effect between the sea level falling and the land rising! You are quite right that the ground between the present shore and the foot of the bank is indeed raised beach, as can be seen even better along the road at Carnain, and was created as the land rose. However, I wasn't referring to that but to the steep bank and the extensive ground behind it which is certainly not raised beach though, as I said, often wrongly called that. If you walk up up the lane which cuts through it to the old quarry where Calum dumps various old vehicles, etc., you can see that the quarry has been dug into a mass of sand and irregular stones typical of what flows out from under a glacier. There are none of the smooth round pebbles which form a beach.
    So, we have a raised beach backed by glacial outwash with its seaward face cutaway by the sea. Agreed?
    As all my friends will say, I hate to be pedantic (!), but the present shore is to the south of the road and the raised beach and bank are to the north, as the road runs pretty much east-west!
    Malcolm

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