284 Notices of Memoirs — West Riding Geological Society. 



33). The description of the section in this highly-perplexing district 

 shows a remarkable similarity lithologically between the beds of the 

 Lammermuirs and those of Gala. It seems to be present also in the 

 cuttings of the Caledonian Eailway above Moffat, and the rise of the 

 sea bottom, in the upper part of the series, seems even to have 

 extended to Barlae. 



From a consideration of all these facts I am of opinion 



1st. That the Gala Group forms a well-marked continuous sub- 

 division of the Lower Silurian of Scotland. 



2nd. That it is immediately superior to the Moffat schists in the 

 order of these Lower Silurians. 



3rd. That, in virtue of this position, and by its peculiar fauna, it 

 is proved to represent part of the Caradoc formation of Siluria. 



I have gratefully to acknowledge repeated encouragement and 

 help from Dr. Page and Mr. D. J. Brown, and also the obligations I 

 am under to Dr. H. A, Nicholson, for assistance, not only from his 

 published writings, but also in personal correspondence. 



iTOTiciBS oip avcEnynoiias. 



On the Mode of Accumulation of the Drift-deposits of the 

 West Eiding of Yorkshire.^ By D. Mackintosh, F.G.S. 



After describing the general characteristics of the Drift-deposits, 

 Mr. Mackintosh gave a minute account of about forty sections 

 which he had examined during the previous six months. Upon 

 the varied phenomena presented by these sections he founded 

 his explanations of the derivation and mode- of accumulation 

 of the Drifts. He described the deposits in ascending order, and 

 first the " Greyish Blue Clay." This has a very uniform cha- 

 racter. The greater part of it is evidently crushed or washed shale 

 and broken limestone. At least seven-eighths of it would appear to 

 have been manufactured out of what may be called the raw shale 

 and limestone of the plain of Craven and ramifying valleys. It 

 must have been principally derived from the Lower Yoredale and 

 Upper Limestone Shales. The boulders would appear to have come 

 chiefly from the low -lying limestones of the Craven district. Most 

 of the stones found in this clay are much rounded, as if they had 

 been rolled, and not merely rubbed on one side. Ordinary wave- 

 action on a sea beach would appear to have been a principal cause of 

 their attrition. Comparatively few of them are uniformly striated. 

 The scratches run all round the stones, and the small grooves cross 

 each other at all angles. The striations, along with the polished 

 surfaces exhibited by these stones, can be easily explained by the 

 irregular and repeated action of coast-ice. To coast-ice, laden 

 with boulders, stones, and debris, and floating on the surface of 

 oceanic currents, we may likewise attribute the distribution of the 



^ Eead before the "West Riding Geological and Polytechnic Society, at their meet- 

 ing held in Sheffield, 29th of April, Lord Wharncliffe in the chair. 



