Account of a Well-sinking made at Swindon. 365 



rock of Conway Mountain. In the latter place spherulites may be 

 found containing this product in alternate concentric layers. Ana- 

 lysis shows it to be allied to pinite ; but the formation in it, when 

 it tends to become crystalline, of microlites of various kinds opposes 

 its being regarded as a simple mineral. The rock of Digoed itself 

 contains 83 per cent, of silica, the black product only 50 per cent. 

 The great nodular masses of quartz and these contrasted soft, black, 

 cleavable layers form striking features of alteration, especially as 

 the residual spherulitic matter closely resembles the matrix, and 

 may in time become un distinguishable from it. A consideration of 

 the pyromerides of the continent makes it appear probable that 

 they also are altered coarsely spherulitic rhyolites, and the compa- 

 risons made by Delesse in 1852 strongly support this view. 



2. " Account of a Well-sinking made by the Great Western 

 Railway Company at Swindon." By Horace B. Woodward, Esq., 

 E.G.S. With Lists of Fossils, by E. T. Newton, Esq., E.G.S. 



This well-sinking was made under the direction of Captain William 

 Dean, while fossils were collected and notes of the strata were made 

 by Messrs. W. H. Stanier and A. E. Elliott, to whom the authors 

 were greatly indebted. The object of the sinking was to seek a 

 supply of water for use in the works at Swindon. The strata proved 

 were as follows : — 



ft. in. 



Made ground 8 



Kimeridge Clay 64 1 



Corallian Beds 40 1 



Oxford Clay and Kellaways Rock 572 9 



Cornbrash 18 3 



ForestMarble 33 



736 2 



Unfortunately for the Company, saline waters were met with in 

 the Corallian rocks and again in the Eorest Marble. 



Eew fossils were obtained from the Kimeridge and Corallian rocks; 

 but those from the Oxford Clay and Kellaways Eock indicated the 

 upward succession of the Callovian ornatus-, and cordatus-i orms of 

 Ammonites. It was shown -that at least 44 feet of clays, sands, and 

 sandstones might be assigned to the Kellaways Eock, which should 

 be regarded as an irregular and impersistent basement-bed of the 

 Oxford Clay. Turning to the subject of the saline waters, it was 

 shown from analyses by Mr. E. W. Harris that the Corallian water 

 contained 144 grains per imperial gallon, consisting chiefly of sodium 

 chloride and sodium carbonate. In the Eorest-Marble water, which 

 had a temperature of 64°, the saline ingredients amounted to 2131 

 grains per gallon, consisting chiefly of sodium chloride, calcium 

 chloride, &c. 



Attention was then drawn to the occurrence of saline waters in 

 the Jurassic rocks, at Melksham, Holt, Trowbridge, St. Clement's, 

 Oxford, and other localities in the neighbourhood; and also to the 

 occurrence of saline waters in the Coal-measures and older rocks of 



