THE GEOLOGIST. 



fig. 8, just beneath the surface of the gTound, it can, however, be dis- 

 tinctly seen that some change is going on, because the joint-lines 

 are rather more distinctly visible and the horizontal lines more 

 numerous; and here we may observe (standing on the bank of the 

 lower quarry, with the eastern or upper face of the older quarry in 

 view, and the prominent mass of Haytor still higher up and further 

 off) a teaching series of appearances in the granite. In the face of 

 the newest quarry we see the joints in their natural condition, almost 

 unaffected by the percolation of surface-waters, and by exposure to 

 weather for the last thirty or forty years ; but in one small portion 

 of this face already alluded to, may be traced in outline the sectional 

 areas of several flattish blocks of granite (fig. 8), of various dimen- 



Lign. 8— Portion of Eastern Face, New Quarry, Haytor. 



sions, bounded by joint-lines, and which would be in the course of 

 time, if exposed to adequate agencies, separated one from the other 

 by the removal of the intervening softer part of the rock, and would 

 either be tumbled down by force of gravity, or would remain piled 

 up more or less regularly one upon another (if the destruction of 

 the rock took place in the air without the intervention of the sea or 

 rivers). There is one such mass, marked out by the intersection of 

 oblique joints (indicated by a in fig. 8) which might possibly weather 

 away into a sufficiently symmetrical form as to remain poised on the 

 underlying hump-backed mass of rock which is so bounded by joints 

 as to promise to withstand the destructive action of wind and 

 weather, should ever time bring about such changes of the surface 

 as would lead to the modification of the Dartmoor district and expose 

 it to the erosive action of air and water in those long continued pro- 

 cesses which have in former times cut out and left the uprising mass 

 of Hnytor on the hill above (fig. 3) : — and the slow, but possibly not 



