OCCURRENCE OF GYPSUM, &c. 217 



gypsum occurs mixed with dolomite, in beds subordinate to mica slate. 

 With regard to Transition Gypsum, its occurrence is less question- 

 able ; but all authorities concur in fixing the principal and most important 

 deposit of gypsum, to the newer red or saliferous sand-stone, (the red 

 marie of England, and hunter sand-stein of Werner) or in its associated 

 •rock, the mountain lime-stone. 



2. It was with these considerations in my view that I have always 

 looked to the hills which bound on the south side, the several duns or 

 vallies that stretch along the foot of the great mountain tract, as the most 

 probable locality in which to find this substance. They answer perfectly 

 in character to the description given of the red marie of England. That 

 they are really a type of the saliferous sand-stone, is proved by the occur- 

 rence of extensive deposits of rock salt in their prolongation towards the 

 Indus. 



3. The gypsum, however, of which I have the honor to submit speci- 

 mens, is not found in those mountains, but in the clay-slate formation 

 which bounds these vallies to the north, and which certainly possesses 

 none of the characters of a secondary rock. It will be differently named 

 by the followers of different systems ; those who admit a transition class, 

 will probably distinguish it by that term ; while those who reject that 

 class will, at once, call it primary : it possesses the characters of the 

 transition clay-slate in its granular composition, in being associated with 

 a fetid lime-stone, and in lying between the secondary and the better- 

 defined primary strata. It is to be noted, however, that the gypsum occurs 

 in very small quantity; it appears to me, indeed, certain, that whatever 

 be the age of the including rock, the gypsum itself is of comparatively 

 modern formation, and similar in its origin to those masses of stalagmitic 

 lime-stone which are found in every rock, from the oldest gneiss to the 



3 H newest 



