NS4178 : Ballagan Beds in Auchenreoch Glen

taken 11 years ago, near to Bonhill, West Dunbartonshire, Great Britain

Ballagan Beds in Auchenreoch Glen
Ballagan Beds in Auchenreoch Glen
Ballagan Beds is the name given to certain sedimentary deposits laid down during the early Carboniferous period. Compare NY3881 : Ballagan Formation.

The type location, and the place which gives the formation its name, is Ballagan Glen: NS5780 : The Ballagan Beds, Ballagan Glen.

As explained by John Mitchell in the book "Loch Lomondside" (New Naturalist Series, 2001), the Ballagan Beds comprise "some 180 metres of alternating beds of cementstones and thin-bedded silty mudstones. Whereas the mudstones are derived from material washed down from the high ground during rainy seasons, the cementstones are impure limestones precipitated during extended periods of drought".

This photograph shows a detail from the steep, bare southern side of lower NS4178 : Auchenreoch Glen (see that item for the context of the present photograph). The stratification is clearly evident here, as it is throughout most of the glen. The wall of rock shown here is made up of layers of crumbly, fractured shale (the mudstone), interleaved with layers containing paler, rounded nodules (of cementstone).

The layers of shale are fragile; poking at the rockface often brings some material down. Many of the cementstone nodules, after having eroded out of the wall of rock, can be seen lying in the bed of the burn; they often have quite distinctive crack-like surface patterns. For just one example of many, see NS4178 : Cementstone nodule in Auchenreoch Glen.
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NS4178, 66 images   (more nearby search)
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Date Taken
Friday, 25 June, 2010   (more nearby)
Thursday, 1 July, 2010
Geographical Context
Geological interest 
Place (from Tags)
Auchenreoch Glen 
Geological feature   (more nearby)
Subject Location
OSGB36: geotagged! NS 4180 7835 [10m precision]
WGS84: 55:58.3200N 4:32.1926W
Camera Location
OSGB36: geotagged! NS 4180 7835
View Direction
South-southwest (about 202 degrees)
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Ballagan Beds 

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