Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/368

 by the derivative rocks I have been describing, and all the different modifications to be found in the district occur in this valley, and the whole of the low hills are composed of them. In the bottom of the valley there is a considerable tract of loose sand. On leaving the grauwacke series near Dunster, we find at Carhampton a low hill composed of a red argillaceous sandstone, and proceeding eastward towards Williton, either that sandstone, or a sandstone containing rounded fragments of the grauwacke formation appears in all those places where the ground is broken. At Tarr, Tor Weston, and Vellow, the same conglomerate (or pebble rock) that I have described at Alcombe, again appears. At Tor Weston the quarries are situated near the top of a small detached hill, the conglomerate forming beds of great magnitude. At Vellow there are sections of it above 50 feet in height, and it rests here upon a bed of red clay. There are distinct parallel lines which divide it into thick beds, dipping northward about 10°. It contains here more fragments of limestone than it does at Alcombe, and I found between the pebbles in some places, small nests of hematite. It is covered as at Alcombe by a sandstone, but of a different variety, being of a deep reddish colour and full of fragments of grauwacke, and without any appearance of copper or of sulphate of barytes. The same sandstone may be seen in different places between Williton and Vellow, particularly near the village of Sampford Brett. A little to the west of Williton church, there is a reddish white sandstone, much harder than any other I met with in this district. It occurs at the eastern termination of the same ridge, on the west side of which the quarries of conglomerate at Tarr are situated, and I think that it is very probably only a variety of that sandstone which covers the conglomerate in other places. If it is stratified the lines of separation are very indistinct. There are many perpendicular fissures in it; part of