By Charles Moore, F.G.S. 



47 



rocks forming the eastern edge of the Somersetshire coal basin in 

 its passage to the north lie under the secondary rocks of this district. 

 The basement limestone beds, but without any superimposed coal, 

 were found in a sinking at Batheaston, and they reach the surface 

 in a small uplift, under Lansdowne, and at Wick, clearly indicating 

 the eastern outline of the basin ; it is therefore quite possible that 

 in the foldings of these beds, the coal measures may be somewhere 

 present under Wiltshire. Within my recollection several ill-advised 

 and abortive attempts to find coal have been made. In two instances 

 shafts were commenced in the Oxford Clay, one of the upper beds 

 of the oolites, and were all the beds between it and the carboniferous 

 series present in their normal thicknesses, it is probable several 

 thousand feet would have to be passed through before the latter 

 could have been reached. The experimental boring put down at 

 Netherfield, near Battle, Sussex, proved that at that spot the 

 Oxford and Kimmeridge Clays were nearly 2000 feet in thickness, 

 though this was probably an exceptional thickness. At Kimmeridge 

 the latter are about 600 feet thick. 



The palaeozoic rocks under Wiltshire are hidden by a wide-spread 

 development of secondary formations, which, in ascending order, 

 include the following : — 



Upper Lias 

 Inferior Oolite 

 Fuller's Earth 

 Stonesfield Slate? 

 Great Oolite 

 Bradford Clay 

 Forest Marble 

 Cornbrash 

 Oxford Clay 

 Coral Rag 



Kimmeridge Clay 

 Portland Oolite 

 Purbeck Beds 

 Lower Green Sand 

 Gault 



Upper Green Sand 

 Chalk 



Tertiary Beds 

 Post Pliocene Drifts and 

 Brick Earth. 



Some of these, especially the Bradford Clay, the Cornbrash, and 

 Forest Marble, are but thin and local, and though useful as divisions, 

 do not exercise the same influence on the general physical characters 

 of the county as the bold escarpments of the chalk, or the level 

 plains of the Oxford and Kimmeridge Clays. This may be said 



