SALIFEROUS MARLS. 



33 



found some years ago in the sandstone of Warwick, and considered by Dr. Buckland 

 to be allied to the genus Phytosaurus, associated with fragments of plants, which are in 

 too mutilated a state to allow the species to be ascertained. 



This view does not coincide with my conclusions respecting the English equivalents 

 of the Keuper ; for I believe that the German formation is represented by our saliferous 

 marls, with the sandstone before described ; and it will presently be shown that masses 

 of rock much resembling that of Warwick, and apparently occupying the same stra- 

 tigraphical position, must be considered to form an integral part of the underlying 

 New Red Sandstone (Bunter Sandstein, Gres bigarre), The occurrence of a Saurian, 

 even if the genus were established, could not prove the beds of Warwick to belong to 

 the Keuper; for we know that in the upper secondary formations, the remains of Hylcso- 

 saurus have been discovered both in the Lower Green Sand and in the Wealden, though 

 the first of these formations is of marine, and the second of freshwater or estuary origin * 

 while with reference to the rocks now under consideration, M. Voltz has taught us, 

 that Saurians occur in the Gres bigarre or Red Sandstone beneath the Muschelkalk, 

 as well as in the Keuper above it. 



The fossils of the overlying and underlying formations inEngland being of marine origin, 

 there is little doubt that the red marl must also have been deposited beneath the sea. 

 In Germany and in France this inference is established by the presence of marine remains 

 in the Keuper, Muschelkalk, and Bunter Sandstein, the three upper formations of the 

 system ; the first of which, as before mentioned, represents our saliferous marls. The 

 second or great calcareous formation has not yet been discovered in the British Isles ; 

 and the third is the equivalent of those massive central sandstones of our system treated 

 of in the following part of this chapter. The numerous brine springs as well as masses 

 of rock salt which are contained in the red marl, seem to offer additional proofs of the 

 marine origin of these deposits, since Dr. Daubeny has shown, that in many of these 

 saline sources there is an admixture of iodine, a principle which is confined to the sea 

 and its productions. This argument is not however to be considered decisive, but only 

 as forming a portion of cumulative evidence, which taken in conjunction with that of 

 the remains occurring in the deposits of this age on the Continent, fortifies the con- 

 clusion that our saliferous marls are of marine origin ; for it might be said that iodine 

 and chloride of sodium have been derived in the first instance from the interior of the 

 earth, and that the ocean may have owed its saltness to beds of rock salt, as well as 

 that rock salt owes its origin to the evaporation of sea-water. 



These considerations lead us naturally to an examination of the origin of the mineral 

 springs so abundant in the Vales of Gloucester, Worcester, &c. 



