﻿372 Rejjorts and Proceedings — Geological Society, 



Origin of Boulder-clay and the Sequence of Glacial Events." By D. 

 Mackintosh, Esq., E.G.S. 



' In this paper the author minutely stated the results of repeated 

 examinations of a number of new sections of drift-deposits, with a 

 particular reference to the character of their bases and lines of 

 junction between them. He described in detail the patterns ex- 

 hibited by the grooved erratic stones of the shelly clays compared 

 with irregularly scratched stones of the Lake District. He then 

 gave a particular account of the character of the two shell}' claj's, 

 and assigned reasons for believing in their threefold origin — the 

 local grit and broken shells accumulated by the sea, which at the 

 time was fully charged with sub-glacial clay, and the erratic stones 

 carried and dropped by floating coast-ice. He described phenomena 

 jDroving that boulders must have fallen into the clay, and called at- 

 tention to the varjdng directions of stri^ on rock-surfaces (including 

 some he had lately discovered), and their relations to the courses 

 and cross-courses taken by erratic stones, some of which had travelled 

 200 miles. He then connected the special observations he had lately 

 made with the results of many years' investigations extending around 

 the basin of the Irisb. Sea, from Carlisle to Crewe, and from Crewe 

 to Anglesey, and traced the horizontal and vertical extent of the 

 three shelly drifts, and their relation to the mountain drifts of North 

 Wales and the Lake District. He stated many reasons for rejecting 

 the idea that land-ice had distributed either of the two Boulder-clays 

 he had described, but left it an open question whether the blue clay 

 of North Wales, the Lake District, the Yorkshire valleys, and parts 

 of Lancashire, with its local stones, may not have been accumulated 

 under land-ice. He concluded by stating that the paper was in- 

 tended to be introductory to one on the correlation of the drifts of 

 the north-west with those of the eastern and central parts of 

 England. 



8. " Discovery of Silurian Beds in Teesdale." By W. Gunn, Esq., 

 F.G.S., and C. T. Clough, Esq., B.A., E.G.S., of H.M. Geological 

 'Surve5^ 



The authors described the general physical characters of Teesdale, 

 referring especially to the position of the Burstreeford Dyke, the 

 whin, according to them, occupying a very different horizon at 

 Eorcegarth Hill and Cronkley Fell, so that the displacement indi- 

 cated by it is probably 400 feet greater than has been supposed. 

 This disturbance has brought up the beds which lie at the base of 

 the Carboniferous series in the dale, and these are exposed in the 

 banks of the Tees at the old Pencil Mill at Cronkley, where they 

 were formerly worked up into slate pencils. They are soft shales, 

 usually gray or greenish gray, sometimes yellowish green or purplish 

 red. They are very indistinctly bedded, but show traces of what 

 may be cleavage in some parts. From the character of the deposit, 

 the character of the dykes of the district, and the fact that these 

 beds are not altered by them, the character of the veins traversing 

 them, and an apparent unconformity between these beds and the 

 imdoubtedly Carboniferous beds overlying them, the authors come 

 to the conclusion that this deposit is not of Carboniferous, but of 



