236 Geological Society: — 



6. " On the Cretaceous Dentaliadae." By J. S. Gardner, Esq., F.G.S. 



7. " On a number of new Sections around the Estuary of the 

 Dee which exhibit Phenomena having an important bearing on the 

 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 

 exhibited 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 shelly clays, 

 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 subglacial clay, and the erratic stones 

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

 mena proving that boulders must have fallen into the clay, and 

 called attention to the varying directions of striae 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 observa- 

 tions he had lately made with the results of many years' investiga- 

 tions extending around the basin of the Irish Sea, from Carlisle to 

 Crewe, and from Crewe to Anglesey, and traced the horizontal and 

 vertical extent of the three shelly drifrs, and their relation to the 

 mountain drifts of Korth 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 JSTorth Wales, the Lake- district, 

 the Yorkshire valleys, and parts of Lancashire, with its local 

 stones, may not have been accumulated under land-ice. He con- 

 cluded by stating that the paper was intended 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., F.G.S., of H.M. Geolo- 

 gical Survey. 



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 grey or greenish grey, 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 



