170 PKOCEEDINGS Of THE GEOLOGICAL. SOCIETY. [Jan. 8, 



abundance and become tbe predominant form. Gryphcea dilatata 

 still continues in existence, but as a distinct and well-marked va- 

 riety, while a number of Gasteropoda and Concbifera have dis- 

 appeared, their places being taken by new forms. Other species of 

 longer range lived on through both the periods, while some, which 

 began in far earlier, persisted to much later times. All the palseon- 

 tological characters of the beds point to the fact that we have 

 reached the horizon known as the " zone of Ammonites biarmatus " 

 of Oppel, the "zone of Ammonites perarmatus and cordatus" of 

 Hebert, and the " zone of Ammonites perarmatus " of Wright. 



In the gorge of the river Brora, at Fascally, the marine stratum 

 just described is seen to be covered by a great thickness of sandstones, 

 which dip to the east, at first at an angle of 12° ; but as we rise in 

 the series this inclination appears to be gradually reduced, till at last 

 it is no more than 4°. These sandstones, the lower beds of which 

 were quarried in order to obtain materials for the wheel-casings and 

 other constructions about the Water-of- Brora coal-pit, must be esti- 

 mated at not less than 400 feet thick. They yield no traces of 

 marine shells, except in certain thin bands ; but they contain much 

 carbonaceous matter in places, with occasional tbin coaly seams, and 

 are evidently of estuarine origin. 



At a height of about 80 feet from the base of this series of sand- 

 stones I found a band containing casts of Pecten, Myacites, and other 

 marine shells, not sufficiently well preserved to enable me to deter- 

 mine the species. About 100 feet higher another marine band 

 occurs, with numerous casts of Avicula braamburiensis, Sow., and 

 other shells, too obscure for identification. The highest beds of the 

 sandstone series also contain marine shells in the 'condition of casts, 

 including Gryphcea dilatata, Sow. (large var.), Pecten fibrosus, Sow., 

 Pecten vimineus, Sow., Pecten, sp., Avicida, sp., Myacites, sp., &c, and 

 form a transition to the marine series above. These beds of sand- 

 stone with marine shells are quarried on the left bank of the Brora, 

 a little below the bridge. It is quite possible that, in the thick 

 mass of estuarine sandstones just noticed, other marine bands may 

 occur which have not yet been detected. 



The great series of sandstone-strata which we have been describing 

 is bent over towards the north in an anticlinal ; this may be traced 

 by observing the dips in the various pits opened on Braamberry and 

 Hare Hills. The lowest marine beds, immediately above the clays, 

 assume at their northern extension a somewhat different character 

 locally, and consist of a hard, brittle, fine-grained sandstone full of 

 casts of fossils. This sandstone has been very extensively dug in 

 the Clynlish or Hare-Hill quarries, and has been employed in the 

 construction of London Bridge and in many local erections, such as 

 Dunrobin Castle, the colossal statue by Chantrey on tbe top of Beinn- 

 a-Bhraggie, &c. It can be obtained in blocks of great size, is easily 

 worked, and is of a beautiful white colour. In places the rock 

 passes into an intensely hard compact material, like quartzite, which 

 was, in the early part of this century, used by the local militia for 

 making gnn-fiints, and, as my friend Mr. Joass showed me by a large 



