190 PKOCEEDINGS 01" THE GEOIOGICAL SOCIETr. [Jan. 25, 



Triassic series was deposited in inland waters, partly fresh, or salt as 

 the case may have been, whereas the continental Trias was partly, at 

 any rate, deposited in areas connected with the sea. If, between the 

 deposition of the New Eed Sandstone and Marl in England, the 

 area in which they occur was not for a time depressed beneath 

 the sea, we have a sufficient reason for the absence of the Muschel- 

 kalk. There are, indeed, symptoms of a gap in time between 

 our Bunter and Keuper strata, accompanied by slight indications of 

 disturbance and unconformity ; and, at aU events, there is in places 

 a very marked overlap of the Marl across the Bunter Sandstone 

 series. 



In England there is a perfect physical gradation between the New 

 Eed Marl and the Rhsetic beds, shown by interstratifications of red, 

 green, and grey marls which, varying in different localities, pass by 

 degrees into limestones, sandstones, and black shales. It is therefore 

 impossible to determine precisely where the Ehsetic beds commence 

 in this series ; and, indeed, aU through the New Eed Marl there is 

 a tendency to a repetition of the same sort of deposits as those with, 

 which the ordinarily recognized Ehsetic beds were ushered in. 

 This is evinced by the frequent local recurrence of green and grey 

 marls, and thin beds of light-grey and whitisb sandstones, commonly 

 called the Middle Keuper Sandstones, which, however, occur in many 

 horizons in the New Eed Marl. 



I have long held, in common with some other geologists, that 

 our New Eed Sandstone was probably deposited in an inland lake, 

 and that our New Eed Marl was certainly formed in a salt lake*. 

 This belief is founded on the existence of the great deposits of rock- 

 salt common in that formation, on the ground that, such lakes being 

 fed by rivers and having no outflow, concentration of salts ensued 

 by evaporation, and saline deposits were at length formed, in this 

 case consisting chiefly of common salt. To me it seems impossible 

 that solid salt can be deposited in quantity in an ordinary ocean, 

 for the salt in solution cannot be sufficiently concentrated there to 

 permit of deposition. And though wide-spreading cakes of salt have 

 been formed by evaporation in such areas as the Eunn of Cutch, 

 yet this seems rather to partake of the nature of an accident than to 

 denote a steady, long-continued train of events like those which 

 marked the deposition of salt in our Keuper series. 



Gypsum and other salts accompanying the New Eed Marl may 

 also have been formed in like manner ; and I consider that the per- 

 oxide of iron which stains both salt and marl may also have been 

 carried into the lakes in solution as carbonate of iron, and afterwards 

 deposited as a peroxide through the oxidizing action of the air and 

 the escape of the carbonic acid which held it in solution. It is weU 



* As far as I know, first proposed by the late Professor H. D. Rogers in an 

 address to the British Association at G-lasgow, 1855, p. 5, " On some of the 

 Geological Functions of the Winds, illustrating the Origin of Salt." Only the 

 title was printed ; but ever since I have adopted and expounded Professor Eogers's 

 views in my lectures. Mr. Moore mentions " the fresh- or brackish-water depo- 

 sits of the Upper Trias," Quart. Journ. Geol. Soc. vol. xxiii. p. 458. 



