THE OLD RED SANDSTONE. 121 
among the nearly vertical strata that lean against the North- 
ern Sutor. The section there presented is washed by the 
tide for nearly three hundred yards from where it rests on 
the granitic gneiss; and each succeeding stratum in the 
ascending order may be as clearly traced as the alternate 
white and black squares in a marble pavement. First there 
is a bed of conglomerate two hundred and fifteen feet in 
thickness, ‘‘ identical in structure,” 
say Professor Sedgwick 
and Mr. Murchison, ‘‘ with the older red conglomerates of 
Cumberland and the Island of Arran,* and which cannot be 
distinguished from those conglomerates which lean against 
the southern flank of the Grampians, and on which Dunnot- 
tar Castle is built. Immediately above the conglomerate 
there is a hundred and fourteen feet more of coarse sand- 
stone strata, of a reddish yellow hue, with occasionally a few 
pebbles enclosed, and then twenty-seven feet additional of 
limestone and stratified clay. There are no breaks, no 
faults, no thinning out of strata—all the beds lie parallel, 
showing regular deposition. I had passed over the section 
twenty times before, and had carefully examined the lime- 
stone and the clay, but in vain. On this occasion, however, 
I was more fortunate. I struck off a fragment. It contained 
a vegetable impression of the same character with those of 
the ichthyolite beds; and after an hour’s diligent search, I 
had turned out from the heart of the stratum plates and scales 
enough to fill a shelf in a museum — the helmet-like snout 
* Different in one respect from the conglomerates of Arran. It 
abounds in rolled fragments of granite, whereas in those of Arran 
there occur no pebbles of this rock. Arran has now its granite in 
abundance; the northern locality has none; though, when the con- 
glomerates of the Lower Old Red Sandstone were in the ccurse of 
forming, the case was exactly the reverse. 
12* 
