Strata in the brook Pulcovca. 
391 
This mass of dark clay, which has slipt from the boggy hollow 
about £, consists of perfectly parallel beds, gently waved, and traversed 
by two thin brown veins, which meet at the bottom, but do not 
displace them. It has a very singular appearance in the middle of 
the stream, the current of which it has nearly blocked up, and 
surrounded by blue clay, on which it stands, alluvial rubbish, and 
huge granite boulders, with a patch of yellow limestone on the hill 
above, not any one of which it seems to have any connexion with. 
Being of a soft substance, and exposed to the most violent part of 
the current, which it has here dammed up, it probably will not last 
many years, and has either been much larger, or a long time may 
not have elapsed since it was brought into its present situation. 
3 D 
Vgju V, 
