JONES — ON THE WEATHEEING OF GKANITE 
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loose splinters and sand. In some instances, in the quarry and on 
the neighbouring banks, this sand, or decomposed granite, has fallen 
out and is scattered down the slopes in thick beds, forming the 
"granit poiu'ri" of continental geologists. This substance covers 
Idgn. 6.— Joints in Granite, Eastern Face of Old Quarry, below Haytor. 
vast areas in some granitic regions, and is used for the purposes to 
which sand and gravel are applied in tertiary and alluvial districts. 
In this old quarry the horizontal joints of the granite are less 
widened than are the perpendicular joints by atmospheric causes act- 
ing on their bounding planes. 
In another quariy, on still lower ground, and but little further 
to the west (from which the granite was chiefly obtained for 
building London Bridge), the vertical and horizontal joints are 
Lign. 7.— Eastern Face of New Quarry, Haytor. 
again well seen on the smooth sides of the pit. Fig. 7 shows 
the eastern face. Here the joints are all closed, and their sides 
are nearly unaffected by change, except some alteration in the 
colour of the stone along their lines. At one spot, shown in 
