2/2 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



of this formation, and of their being when present for the most part 

 in the state of casts, I have been unable to ascertain the newest beds. 

 The compact and crystaUine nature of the rock presents a imiver- 

 sahty of character along the whole line of its range which does not 

 lessen the difficulty. 



In very few instances have good sections been met with, because 

 of the peculiar saddles, which seldom expose more than the upper 

 layers. Even when a section is obtained, through the heart of any 

 of these saddles, we gain no information further than that it is com- 

 posed of 2000 feet and upwards of layers of unfossiliferous compact 

 or crystalline limestone. 



Section (J&g. 8) at Miingerrah. — The most detailed section that 

 came under my observation is at Mungerrah, two long days' journey 

 N.N.W. of Dizfiil, in the interior of the Liirish Mountains, where 

 the English and Russian Commissioners passed the summer of 

 1850. 



The valley of IVIungerrah is an extensive and irregular basin, 

 enclosed on all sides by perpendicular cliffs, except on the south, 

 where it is entered by a narrow valley called Ser-i-Deriah. The 

 strata of which the bowl of this valley is composed are red gravel 

 and sandstone. Upon these rest conformably solid beds of lime- 

 stone, which rise to the summits of the mountains around forming 

 the sides of the basin. The dip of the whole series is 8° 30' towards 

 the south. 



The following is a section from the top of the great cliff at the 

 foot of which our camp was situated (see fig. 8, p. 331) : — 



1 . Limestone-breccia, derived from the underlying beds, and 



cemented in a yellow calcareous matrix. 



2. (fig. 8, 3 a) Grey compact limestone, sometimes of a light slate 



colour ; fracture saccharoidal ; emitting a bell-sound, when 

 struck with the hammer ; surface rough, weathering in deep 

 and large holes, as if bored by gigantic lithodomous mollusca. 

 It contains a few OstrecB, Pectines, Echini, casts of Cerithia, 

 and Univalves, which, however, it is impossible to extract, 

 owing to the flinty hardness of the rock. In the upper 

 layers are huge tabular masses of opake, white, and dark- 

 brown flint. 



3. (3«) Thick bed of very hard, compact, somewhat argillaceous, 



light-grey limestone, with fossils similar to the above. 



4. (3 «) Compact greyish-yellow limestone ; the lower portion in 



very thin layers. Fossils very rare. 



5. (36) Very hard gravel-conglomerate, in a deep-red argillo-cal- 



careous matrix ; the pebbles consist of highly indurated, 

 dark-red and dull-green clays and cherts, mixed with a few 

 of dark-blue limestone and yellow sandstone ; the fragments 

 of chert and clay being small and much worn by transport. 

 G. (3 c) Yellowish and reddish sandstone, with thin and regular 

 layers of the above pebbles, which are most frequent in the 

 upper part of the bed. 



