306 MR. H. B. AVOODWARD ON A WELL-SINKING AT SWINDON. 



Forest-marble were penetrated, and a good supply of water was 

 obtained. The section was as follows : — 



ft. in. 



Cornbrash. Brash 9 6 



fHardClay 4 10 



Forest-™.b,e. Bl^Cla, ........ ,....,....„^ 7 



[Blue Clay 3 



Great Oolite. Eock (blue oolitic limestone) ... '33 9 



99 8 



Water gushed in from the south side of the well at the rate of 

 8000 gallons an hour. This contained 28 grains of solid matter per 

 gallon, consisting chiefly of carbonate of lime, with chloride of 

 sodium, carbonate of magaesia, sulphate of lime, &c. Dr. H. Letheby, 

 who made the analysis, stated that although a little hard, it was in 

 all other respects a good and wholesome water *. The river-waters 

 near Chippenham contain similar ingredients. 



In reference to the Swinden well, one would be disposed to doubt 

 that fresh water is likely to be met with in carrying the shaft at the 

 station to a greater depth, although, judging from the waters at 

 Malmesbury and Chippenham, there is no reason why good water 

 should not be obtained in the neighbourhood. 



The Lower Oolitic strata outcrop successively to the north-west 

 of Swindon, and, so far as the surface-evidence is concerned, the 

 following formations would be expected to occur in carrying this 

 boring to a greater depth : — 



feet. 

 Forest-marble : clays and sandy shales, fissile shelly 



oolite and flaggy limestone 80-100 



Great Oolite: compact limestone, shelly oolites and 



marls 140 



Fuller's Earth : clay with occasional beds of hard marl 



or limestone 70 (or more). 



Inferior Oolite : oolitic and shelly limestone and marl 80-100. 



Water is likely to occur in the Great Oolite, upheld by the 

 Fuller's Earth, which throws out so many springs on the Cotteswold 

 Hills ; or, again, water would be expected in the Inferior Oolite or 

 underlying sands upheld by the clays of the Lias. But it is possible 

 that the water that rises from the bottom of the Swindon well may 

 include the supply held up by the Fuller's Earth, if present. 



6. In the case of the saline waters of Swindon, Melksham, &c., 

 having regard to their local distribution, and to the occurrence of 

 comparatively fresh water in neighbouring wells, there can be 

 little question that they rise from a considerable depth, and that 

 the supplies of water in the upper strata are rendered saline by the 

 waters that come from below. 



Several lines of fault running generally in a north-easterly direction 

 between Frome and Swindon are marked on the Geological Survey 



* From notes furnished by Mr. Bryan Wood, of Chippenham, to Mr. H. W. 

 Bristow. 



