336 CLAY GENUS- Geographic Situation. " It is found very univerfally diftributed ; hence its localities are very numerous ; we fhall therefore only mention a few of thofe of Scotland. At’Eafdale and the neighbouring ifles there are great depofitions of tranfirion ? clay flate : between Elvanfoot and Mof fat there are ftrata of tranfiticm flate, which alternate with grey wacce; near the Crook, between Edinburgh and Moffat, there are quarries fituated in the fame fpecies of rock; and in many other parts of the great chain of mountain groupes that traverfe the fouth of Scotland it is to be found. The clay flate of Baly* chulifh in Argylefhire, as far as 1 can judge from fpecimens and information, appears on the contrary to belong to the primitive rocks. Ufe. When it fplits into thin and firm tables it is em ployed for roofing houfes. The greyifh black flraight flaty variety is ufed for writing on ; and the fplintery for pencils, and fome varieties are fo f irfll that they can be ufed as whet-ftones. Obfervatio*'
