318 EROSION OF THE CLIFFS OF MOUNT ROGDO BY A FORMER SEA. 
distance on its loftier sides, the upper portion of which might, therefore, from this 
circumstance alone, be set down as an islet of the former Caspian ; but we will now 
give independent reasons for our belief on this point. The chief escarpment of this 
hill which faces to the east, has been before described as consisting in ascending 
order of argillaceous marl, soft thin-bedded sandstone with harder siliceous reddish 
grit, red and white argillaceous marl, and a cap of grey-coloured limestone (p. 195 
and woodcut). 
The marly and easily decomposing beds, occurring between the hard limestone 
summit, and the sandstone and grit which form the shoulders ol the hill, are neces- 
sarily much ravined and worn by ordinary action ; but beneath them, and at a 
moderate height above the talus of sands with Caspian shells, the nearly vertical 
face of the sandstone has been so singularly eroded, that we can attribute it 
to nothing but violent tidal action. It presents a line of hollows slightly ^ |gj g 
devious from horizontality, which, trumpet-mouthed, laige, and 
much worn at their outer extremity, contract rapidly as the 
advance into the body of the rock which they penetrate 
obliquely upwards, traversing the laminas of deposit, and 
terminating in small cylindrical ends, as represented in 
this section. Such appearances ( b ) being evidently 
of mechanical origin, and wholly independent of 
structure of the rock (since they traverse the beds 
cannot, we think, be so well explained by any known 
natural cause, as that of the upward lashing 
of the sea-surge ; and when we 
see the shells of a former 
: 
Caspian (d) lying in an inclined talus precisely like those of a sea-sliore, and at a 
few feet beneath the line of erosion on the rock, we can scarcely doubt that such 
has been the agent *. 
In another portion of the hill, but on the same eastern face, a similar line of holes 
(c) is seen at a lower level, and beneath it is also a talus of sand and shells ; and 
from this we were led to infer, that the retreat was accomplished by at least two 
great oscillations of the surface. 
1 Mount Arsagar in this steppe, which we did not visit, is also considered by Pallas to have been washed 
bv the waves of the sea, as he found Caspian shells and rolled pebbles upon the summit of its alabaster 
rocks. 
