VOL. XVII. (3) APPENDIX— WATERS OF CHELTENHAM 311 



APPENDIX 



ON THE LOCAL WATERS OF THE TOWN OF 



CHELTENHAM 



BY 

 J. H. GARRETT, M.D., P.L.S., 



Medical Officer of Health. 



Mr Richardson's map of the surface geology of this locahty 

 shows the Lias clay overlain in places by considerable patches 

 of sand. This sand varies in depth from a foot or two, where 

 it shelves off on to the exposed argillaceous surface, to 50 feet 

 or more in its central or deeper parts. 



The certain source of local water-supply which beds of 

 sand lying in such situation afford, have very generally decided 

 the site for a village, and there can be no doubt that the 

 village of Cheltenham occupied its original position as the 

 result of a recognition of this convenience. The extension of 

 the town on to the surrounding clay was an after event for the 

 main part, which took place after the introduction of a general 

 water-supply conveyed from a distance in pipes, the clay ground 

 being a much less reUable source of local water supply than the 

 sand by means of wells. 



Geologists think it probable that the yellow sand was 

 derived directly or indirectly from the Triassic sandstones. 

 There is, however, in places a considerable amount of gravel in 

 the sand. This gravel consists of well-rolled pieces of Oolite and 

 Lias limestone and has the effect of considerably hardening the 

 water that passes through the deposit. Gradually the Car- 

 bonate of lime in this sand must be reduced until the whole 

 will be dissolved, and presumably this process of washing the 

 lime from the sand has been in long and continuous operation. 



The solution of the carbonate of hme, being dependant 

 upon the presence in the water of free carbonic acid to form a 

 soluble bicarbonate of hme, is assisted by the production upon 



