558 Mr. Winch on the Eastern Part of Yorkshire. 
places ; nor is the dyke known in Walker colliery detected in any 
of the mines adjoining. 
The rock where it is quarried for mending the roads in the vici- 
nity of the Tees is of a dark iron-grey colour, and fine grained 
texture. It consists of blocks, lying horizontally and coated with 
ochre, as is also the case at Coley hill, and various places in Nor- 
thumberland. Where the dyke crosses the Pickering road at Sill 
Howell its texture is fine grained. 
