MR. H. B. WOODWARD ON A WELL-SINKING AT SWINDON. 307 



Map, and it is possible that some saline waters burst out along these 

 lines of dislocation. One can understand the introduction of saline 

 waters from below into the Great Oolite series, if the Lower 

 Jurassic clays be absent ; but their occurrence in the Corallian series, 

 having regard to the intervening mass of Oxford Clay, is puzzling. 



The conclusion that suggests itself is, that the saline waters issue 

 from Palaeozoic strata, against a ridge of which the Lower Secondary 

 strata abut in more or less attenuated form. This underground ridge 

 may be some miles to the south of Swindon. 



Naturally the question arises, should not some more positive 

 evidence of the proximity of older rocks be furnished to justify this 

 suggestion ? 'No indications of shore- conditions are revealed in the 

 Oolitic strata. But I may call attention to the fact that in the 

 neighbourhood of Frome, where the Secondary strata come very near 

 to the Palaeozoic rocks, no very marked changes are met with in the 

 Lower Oolites. The Inferior Oolite, it is true, presents here and 

 there conglomeratic beds, but its ordinary oolitic character is generally 

 maintained. The Fuller's Earth, Forest-marble, Cornbrash, and 

 Oxford Clay are all exposed within three miles of the eastern end 

 of the ITendip Hills (formed of Old Eed Sandstone and Lower 

 Carboniferous rocks), and these Oolitic strata show no departure 

 from their ordinary characters. There are here, as elsewhere, sandy 

 beds in the Forest-marble (Hinton Sandstone of Wm. Smith) and 

 sandy beds at the base of the Oxford Clay and in the Corallian series. 

 But we have no positive evidence in this neighbourhood of marginal 

 deposits above the Inferior Oolite ; so that while the older rocks of 

 theMendips, &c., may have stood out as islands here and there, yielding 

 conglomerates in the jS'ew Red, Rhaetic, and Lias times, these ridges 

 of land disappeared beneath the waters in Inferior-Oolite times, and 

 were probably smothered up by the newer Oolitic strata, which in 

 places may nevertheless have rested directly upon the older rocks. 

 Perhaps the underground structure in the neighbourhood of Swindon 

 may present similar features, and we have, at any rate, the evidence, 

 between Bath and Chipping Sodbury and elsewhere, of inliers or 

 islands of Carboniferous rocks appearing in the midst of the Lias. 



Discussion. 



The President remarked on the important data recently obtained 

 by members of the Geological Survey from deep wells, and on the 

 interesting evidence of thickness and relations of strata thus ob- 

 tained. He inquired whether the effect of continuous pumping had 

 been tried in order to reduce the saline character of the water. 



Mr. De Range remarked on the light thrown upon Oolitic rocks 

 by Mr. H. B. AVoodward's studies. The British Association Com- 

 mittee of Inquiiy into Underground Waters had paid much attention 

 to the porous formations. The present section threw some light on 

 Prof. Hull's views as to the thinning of the Lower Triassic rocks in 

 the centre of England. The speaker showed how various members 



