152 



THE GEOLOGIST. 



on the salt being dissolved^ subsided to the bottom of the 

 tube, and consisted of red globules about one-sixteen thou- 

 sand part of an inch in diameter in clusters, and apparently 

 not crystalhne ; but he could not absolutely state that they 

 were monads. The other matters detected were a small 

 portion of rhomboidal crystals, small clear crystals apparently 

 of quartz, the largest about one thousandth part of an inch 

 in diameter, and a fibrous substance, which, after along ex- 

 amination, was considered not gypsum, but vegetable fibre. 

 The second part commenced with a statement of Mr. Ly ell's 

 opinion, that the source of salt might be as deep-seated as 

 that of lava, and that the theory which had obtained most 

 favour with geologists, attributed the formation of salt in 

 various parts, not to precipitation from an aqueous men- 

 struum, but to sublimation from volcanic exhalations rising 

 from below, which insinuated themselves into rents and 

 cavities. The opinion of Dr. Daubeny and others was 

 given, that mineral springs were most abundant in volcanic 

 regions, but that when remote from their site usually coin- 

 cided with some great derangement in the strata, as a 

 fault or fissure, indicating that a channel of communication 

 has been opened with the interior of the earth at some former 

 period. The second part was subdivided into three heads : — 

 The first treated on the traces of volcanic action in the 

 vicinity of the salt ; the second, on the question whether the 

 : alt had been injected by volcanic action, or precipitated from 

 an aqueous menstruum ; the third, on the nature of the 

 aqueous menstruum. With respect to the first subdivision, 

 traces of violent volcanic action were shown by extensive 

 faults bounding the eastern side of the Cheshire salt field, 

 and by the existence of beds of toadstone bordering on those 

 faults, as at Buxton, Matlock, &c. The action of the same 

 power was shown by two lines of elevation, mentioned by 

 Mr. Murchison, reaching from Shrewsbury to Staftbrd shire ; 



