600 



ME. J. EADCLIEEE ON GEO 0 YES A3$D 



part of the seam only, the cause must have been from above, and not 

 from below ; the groove could not be made from below without 

 affecting the strata below the coal, and the coal in which the groove 

 is made. In the case of our faults &c, the cause is from below, for 

 we often find them in a lower seam, and entirely absent from the 

 upper ones. 



In the cross-sections of the grooves are seen layers of the same 

 kind of shale, varying in colour exactly the same as on each side 

 where the coal-seam is intact ; these layers increase in thickness at 

 the lower part of the groove, and gradually lessen in thickness as 

 they near the top of the groove, until they become parallel to the 

 layers in the strata on each side of the groove, the sides of which 

 are raised up a little, as if they had been pressed by the passage of a 

 body along the groove. Where the sides are so pressed the " bord" 

 or " cleat " of the coal is destroyed, and often a mixture of coal and 

 earthy matter is present. The groovings always commence with a 

 narrow " scour " or small groove, then increase in breadth and depth, 

 and afterwards thin entirely out. 



Fig. 1. — Plan of the Roger Mine, Buhinjielcl. 

 (Scale 100 yards to 1 inch.) 



The tinted bands indicate grooves. 



On the plan (fig. 1) is shown the position in which several of 

 these boulders were found. 



One of the boulders exhibited, with the block of coal upon which 

 it lay, showed that the upper side of this block of coal is inferior 

 in quality, a common occurrence immediately round about the 

 boulders ; the coal under the boulder shows a considerable amount 

 of compression. 



