NS3178 : An unconformity at Ardmore Point

taken 9 years ago, near to Ardmore, Argyll And Bute, Great Britain

An unconformity at Ardmore Point
An unconformity at Ardmore Point
A locally available leaflet, "The Geology of Ardmore Point", draws attention to several areas of interest to be seen alongside a footpath that leads around the head of the peninsula, following the top of the beach.

One of those areas is shown in this photograph. The visible outcrops of rock are all composed of sandstone, but those nearby are dark and dull in colour, as were those behind the photographer, while those further away are a much brighter red; the leaflet cites this area as an example of an unconformity, indicating a period when no sandstone was being formed (by deposition) here.

Further information about the geology of Ardmore Point can be found in chapter 3 of "Geology explained around Glasgow and South West Scotland, including Arran" (Judith A. Lawson / James D. Lawson, 1976). Among other things, the book explains that the brighter red rock is Upper Old Red Sandstone, and that "here it rests unconformably, with an irregular base, on the Lower Old Red Sandstone", the latter being the duller, darker rock. The kinds of pebbles that can be found as inclusions in these rocks suggest that the material was washed down here from the north. In the part of the Devonian Period when these rocks were being formed, the area shown here was part of a desert, just south of the equator.

The background shows the shoreline from Craigendoran through Helensburgh to Rhu.
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NS3178, 94 images   (more nearby )
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Date Taken
Friday, 3 September, 2010   (more nearby)
Thursday, 9 September, 2010
Geographical Context
Geological interest  Coastal 
Place (from Tags)
Ardmore Point 
Geological feature   (more nearby)
Subject Location
OSGB36: geotagged! NS 3128 7860 [10m precision]
WGS84: 55:58.2397N 4:42.3040W
Camera Location
OSGB36: geotagged! NS 3129 7855
View Direction
North-northwest (about 337 degrees)
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Other Tags
Unconformity  Old Red Sandstone 

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Image classification(about): Geograph
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