34 MINERAL SPRINGS OF GLOUCESTERSHIRE AND WORCESTERSHIRE. 



Mineral Springs of Gloucestershire and Worcestershire. 



The true nature and geological position of the strata through which these springs rise 

 had not been described before the year 1833, when I made them known in a brief 

 sketch of the geology of the environs of Cheltenham. In one of the previously pub- 

 lished analyses, the Cotteswold Hills were assumed to be "magnesian limestone," and 

 the blue clay through which the waters ascend, was said to cover the limestone. That 

 this clay, the lower Lias, passes beneath the calcareous rocks, is a fact now known to 

 every geologist (See woodcut l.p. 14. and PL 29. fig. 1.); and instead of the magnesian 

 limestone, which does not exist in this district, the stone of the adjoining hills is proved 

 to be the Inferior Oolite. Again, in a recent work, the production of an able chemist, 

 the waters are supposed to rise through sand 1 . It was therefore desirable to show 

 distinctly, that the lowest marly and argillaceous beds of the Lias formation, are really 

 the strata through which these waters find their way to the surface. For a long time 

 after their first discovery at Cheltenham, it was the general belief that they had only 

 one source ; but numerous sinkings, at depths from eighty to one hundred and thirty 

 feet, adjacent to, and at considerable distances from the old springs, have established the 

 fact, that many strata were saturated with water, holding in solution the chloride of 

 sodium, the sulphates of soda and magnesia, and other mineral substances. 



From the analyses of the.se waters by several chemists, it appears that their principal 

 constituents are the chloride of sodium or sea salt, and the sulphates of soda and mag- 

 nesia i sulphate of lime, oxide of iron, and chloride of magnesium, being present in some 

 wells only, and in much smaller quantities 2 . The analyses have also proved, that 

 these substances vary much in their relative proportions at different sources, a circum- 

 stance which must arise from the waters changing their composition with the varied 

 mineral structure of the strata which they traverse. Besides the ingredients just men- 

 tioned, iodine and bromine have, as already stated, been detected in several of the 

 sources by Dr. Daubeny 3 , who has endeavoured to ascertain whether these two active 

 principles, which the French chemists had recently discovered in modern marine pro- 

 ductions, did not also exist in mineral salt waters, issuing from strata which geologists 

 consider to have been formed beneath the sea; and his examination has established the 



1 Thermal and Mineral Springs, by Dr. Gairdner, 1832, p. 419 : an excellent work. The mistake in this 

 case is that of confounding the superficial sandy detritus of the district, with the formation on which it rests. 



2 The waters were formerly analysed by Brande and Parkes, subsequently by Dr. Scudamore and Dr. Daubeny. 

 Professor Daniell has examined those of Pittville, and Mr. Cooper has recently made a very elaborate analysis 

 of those of Montpelier, with the details of which I am not acquainted. His observations, I believe, coincide 

 with those of Dr. Daubeny, in the detection of iodine and bromine. 



3 Philosophical Transactions, May, 1830. 



