188 THE OLD RED SANDSTONE. 
interesting to the antiquary —which has been described by 
some writers as formed of a species of stone unknown in the 
district, and which, according to a popular tradition, was 
transported from the Continent— is evidently composed of 
this Quartzose Sandstone, and must have been dug out of 
one of the neighboring quarries. And so coherent is its tex- 
ture, that the storms of, perhaps, ten centuries have failed 
to obliterate its rude but impressive sculptures. 
The limestones of both the upper and lower formations of 
the system have been wrought in Moray with tolerable suc- 
cess. In both, however, they contain a considerable per 
centage of siliceous and argillaceous earth. The system, 
though occupying an intermediate place between two metal- 
liferous deposits, — the grauwacke and the carboniferous 
limestone, — has not been found to contain workable veins 
any where in Britain, and in Scotland no metallic veins of any 
kind, with the exception of here and there a few slender 
threads of ironstone, and here and there a few detached crys- 
tals of galena. Its wealth consists exclusively in building 
and paving stone, and in lime. Some of the richest tracts of 
corn land in the kingdom rest on the Old Red Sandstone — 
the agricultural valley of Strathmore, for instance, and the 
fertile plains of Easter-Ross: Caithness has also its deep, 
corn-bearing soils, and Moray has been well known for cen- 
turies as the granary of Scotland. But in all these localities 
the fertility seems derived rather from an intervening subsoil 
of tenacious diluvial clay, than from the rocks of the system. 
Wherever the clay is wanting, the soilis barren. In the moor 
of the Milbuy, — atract about fifty square miles in extent, and 
lying within an hour’s walk of the Friths of Cromarty and 
Beauly, — a thin covering of soil rests on the sandstones of the 
