ON S3ME NEWLY EXPOSED SECTIONS AT BEADING. 451 



30. On some newly exposed Sections of the "Woolwich and 

 Reading Beds " at Reading, Bekks. By Prof. T. Rupert Jones, 

 F.R.S., F.G.S., and C. Cooper King, Esq., R.M.A., F.G.S. 

 (Read February 24, 1875.) 



[Plate XXII] 



Contents. 



I. Introduction. 

 II. The Bottom Bed. 

 III. The Blue Clays in the Buff Sand. 



IV. The Mottled Clays. 

 V. The Superficial Gravel. 

 VI. Theoretical Conclusions. 



§ I. Introduction. — Coley Hill, in the south-western suburb of 

 Reading*, is composed of " Woolwich and Reading Beds," lying on 

 Chalk. It is south of the similarly constituted Castle Hill, and 

 divided from it by a small but deep valley, opening on the Kennet, 

 which here runs from south to north at the eastern end of each of 

 these little hills, and divides them from the high ground on which 

 the Katesgrove Kiln is situated. 



This last-mentioned locality was visited and described by Dr. Buck- 

 land in 1814 (" Catsgrove-Hill Brick-kilns," Trans. Geol. Soc. vol. v. 

 p. 278), by Mr. Rolfe about 1833 (ibid. ser. 2, vol. v. p. 127), by 

 Mr. Prestwich about 1852 (Quart. Journ. Geol. Soc. vol. x. p. 87), and 

 in 1858 by the Geological Surveyors, who reported on it in 1861 and 

 1872 ('Memoirs Geol. Survey, Explan. Sheet 13,' 1861, p. 29, and 

 vol. iv. 1872, p. 188). At the same time they surveyed Castle and 

 Coley Hills* above mentioned (ibid. p. 39, and ib. p. 197). At none 

 of these places in 1858 were exposures of the Lowest Reading Beds 

 and the Chalk open to view. 



Of late years, however, a greater local demand for lime has led to 

 the excavation of Chalk at Coley Hill f; and since 1869 we have 

 made repeated observations, as further sections of these Lowest Ter- 

 tiary strata have been exposed at the pits on the north and south 

 sides of the eastern end of the hill J. 



§ II. The Bottom Bed. — On the very even but perforated surface 

 of the Chalk, noticed by Buckland, Rolfe, Prestwich, Whitaker, and 

 others as occurring in Berks and Hertfordshire, the loamy and 

 pebbly green sands§, constituting the "Bottom Bed" (Whitaker), were 

 found to carry the usual abundance of Oyster-shells, with casts of 



* "David's Hill," Buckland, "St. David's Hill," Prestwich ; opp. citt. 



t We have been told that at the Castle-Kiln pit, now disused and partly 

 built over, extensive underground excavations in the Chalk were formerly carried 

 on. 



\ The north pit is worked by Mr. Collier, and the south pit by Mr. Wheeler. 



§ Some seams in this part of the formation consist of brown clay traversed 

 vertically and obliquely by irregular subcylindrical lumps of green sand, as if a 

 mud had been channelled by animals (lobster-holes for instance), or perforated 

 by stems and masses of sea-weeds, and the cavities so produced subsequently 

 filled up with sand. 



