434 ON THE SUPERFICIAL STRATil: 
miles farther west, the quarries of old red sandstone on the 
margin of the valley shew, reposing on the rock, fine sand 
with the usual regular forms'^ over which, under the soil^ 
a few feet of wafer-like scales of the sandstone, with sand 
intermixed. 
In general, it may be remarked, that the granular coal, 
bituminous shale, and other products of the coal-formation, 
do not appear among the sands and gravels of this upper 
district, which have now been described. But the specimens 
manifest the presence of sundry pebbles of the transition- 
rocks ; also of mica-slate= 
Old Red Sandstone of Upper District of the 
Forth. 
This appears, on its lower boundary, at Airthrey MineSy. 
Bridge of Allan, Cruives of Craigforth, Dripfarm, and 
Redhall. It also forms Naad Enowe, a conical knoll, 
elevated above the Garse. The common dip and direction 
of the sandstone at all these points corresponds with that 
exhibited in the channel of the Teath and the Allan. This 
rock appears also within a few yards of Craig-forth, a mass 
of greenstone, which, rising through the Carse, presents, on 
one side, a perpendicular precipice. Here the sandstone is 
traversed by veins of greenstone, which may be seen in the 
bed of the Forth, and on the north side they were several 
yards in thickness, in the quarries for the roads. These 
last veins were of several yards in thickness. 
The writer of the article Perthshire^ in the Edinburgli 
Encyclopaedia, states his opinion, that the Transition red 
sandstone is bounded on the south by the Ochil and Camp- 
sie Hills. I have marked on the map what appears to be 
its course on die south. From Redhall, in the- direction of 
