j\Ir. R. Mortimer on a Well-section in the Chalk at Driffield. 239 



Roman Fell, whence the author proposes to call these deposits the 

 Roman- Fell beds. These beds represent the series b, and also the 

 lower part of a, at Ash Fell. Following their outcrop towards Cumber- 

 land, the conglomeratic beds from the middle downwards increase 

 much in thickness and become much coarser. The author regards the 

 Roman-Fell beds as approximately on the horizon of the Calciferous 

 Sandstone series of the sonth of Scotland ; and he remarks that they 

 are locally undistinguishable from much of the Basement series, and 

 have been described by authors as undoubted Old lied Sandstone. 



3. " An Account of a Well-section in the Chalk at the North end 

 of Driffield, East Yorkshire." By R. Mortimer, Esq. Communi- 

 cated by "W. Whitaker, Esq., F.G.S. 



In this paper, which was in continuation of a former communica- 

 tion to the Society (Q,. J. G. S. vol. xxix. p. 417), the author stated 

 that the well-section referred to passed through 7 feet of clay and 

 47 feet of chalk, the upper 3 or 4 feet of the latter very rubbly and 

 broken. The chalk was bedded in laminae of from T L in. to 16 in. 

 thick. From a depth of 20 feet downwards the well exposed many 

 nearly vertical partings running in all directions through the Chalk ; 

 and the surfaces of the blocks thus marked out showed numerous 

 striae, such as were described in the author's former paper. These 

 striae were in most cases horizontal; but some surfaces showed them 

 at an angle of 45° to the horizon. The laminae of which the chalk 

 was composed were separated by layers of a softer substance like 

 fuller's earth, containing 1*67 per cent, of organic matter, 7*05 per 

 cent, of oxide of iron, 10-23 per cent, of alumina, and 34-80 per 

 cent, of silica. The author regards this soft substance as formed by 

 the disintegration of chalk, shells, &c, caused probably by the 

 periodical prevalence of great waves or other disturbances in the 

 Cretaceous sea. The effect of its formation he considers would be 

 to check the upward growth of the mass of chalk, which he now, as 

 formerly, ascribes to the direct secreting action of numerous zoophytes. 

 In support of this view he states that the surfaces of the chalk 

 laminae are more or less irregular — and not even, as if produced by 

 quiet sedimentary deposition. The paper contained detailed analyses 

 of the chalk and of the soft partings. 



4. "On Slickensides or Rock-striations, particularly those of the 

 Chalk." By Dr. Ogier Ward. Communicated by Prof. Morris, F.G.S. 



The author referred to previous communications on this subject, 

 and maintained that the striae observed in chalk are to be regarded 

 as slickensides caused by disturbance and movement of the rock. 

 He described the appearances in detail, and mentioned the occur- 

 rence of similar striations in various rocks. 



April 15th, 1874.— John Evans, Esq., F.R.S., President, 

 in the Chair. 

 The following communications were read : — 

 1. " About Polar Glaciation." By J. F. Campbell, Esq., F.G.S. 

 The author commenced by referring to a reported statement of 



