NS4278 : Geological dyke crossing a stream valley

taken 4 years ago, 3 km from Bonhill, West Dunbartonshire, Great Britain

Geological dyke crossing a stream valley
Geological dyke crossing a stream valley
As is also apparent from within the NS4278 : Stream valley itself (see that picture for a view of this crossing from the side), a geological dyke cuts across the line of the stream valley here.

The dyke is most obvious at points like this (other dykes nearby form more spectacular examples, such as the one shown in NS4178 : The Gates of Sodom), but the present picture is intended to show that the course of this geological feature is also discernible on the ground even outside the confines of the stream valley; note that the dyke's continuation on the far side of the valley is apparent in this picture: it can be seen receding into the distance (heading NNE) as a line that is more green that its surroundings because of having less dried-up vegetation on it.

In places, it could be mistaken for an old boundary; several such boundaries are located nearby. In fact, followed in the opposite direction for a short distance, the line of this geological dyke does coincide with an old boundary, part of which is depicted on the 1:25000 map. Note the corner of that boundary that is shown in NS4278 : Corner of an old field boundary; it is 290 metres to the SSW of the point from which the present picture was taken.

The following is speculation on my part:

It seems unlikely that an old boundary would coincide so closely, by chance, with an underlying geological feature here. Except where it crosses the stream valleys, the underlying geological dyke does not have the kind of wall-like appearance that would make it suitable to serve as a boundary by itself. Nevertheless, for those living centuries ago, its noticeable (and very straight) course across the moor in this area may have made it seem the natural place to create a boundary.
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NS4278, 98 images   (more nearby search)
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Date Taken
Tuesday, 25 October, 2016   (more nearby)
Thursday, 17 November, 2016
Geographical Context
Geological interest 
Subject Location
OSGB36: geotagged! NS 4243 7879 [10m precision]
WGS84: 55:58.5694N 4:31.6031W
Camera Location
OSGB36: geotagged! NS 4243 7878
View Direction
North-northeast (about 22 degrees)
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Geological Dyke 

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Image Type (about): geograph 
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