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These are called by the miners " bell moulds," from their shape, 

 and are frequently the cause of serious and fatal accidents, owincr 

 to their suddenly detaching themselves from their matrix and 

 falling without warning on those below. A most admirable 

 instance of an overlap fault, with the ends drawn backwards 

 and downwards, was pointed out by Mr. McMurtrie. In 

 further illustration of the abnormal condition of the veins in 

 this coal field, the workings on the opposite side of the shaft were 

 visited, and the " Bull" vein was again struck, after rather a diffi- 

 cult process on hands and knees. Here the overlaps seem to 

 assume the form of the letter Z, and are a regular puzzle to account 

 for. Another peculiar feature, too, is seen here. Immediately 

 over the "Bull" vein, which is more than two feet thick, a very 

 thin vein of coal comes in, separated from the former and from the 

 harder roof beds above by thin bands of soft shale. This top vein 

 is twisted and contorted in the most extraordinary manner, quite 

 independent of and unconformable with the beds above and below. 

 In some places the vein dies out, in others it is wedged into two 

 bands of shale. How is this to be accounted for 1 Why should 

 not the same disturbance which affected this thin vein have also 

 affected the beds above and below, which are only separated by a 

 few feet 1 Mr. McMurtrie seems to give the only plausible expla- 

 nation, ie., that this little vein, with its accompanying shale, was 

 in a more plastic state than the greater vein below, and the pressure 

 acting from above and on the sides caused an unequal movement 

 in the two veins, hence the more numerous twistiugs and contor- 

 tions of the former. As an instance of the constant movements 

 going on throughout the coal fields, the roadway which some ten 

 weeks since was from 6 to 9 feet high, had within that space of 

 time so filled up, both from the natural rising of the floor, the 

 lowering of the roof, and the movement of the sides, that in some 

 places it was necessary to stoop nearly double to clear the balks 

 overhead, which were in many cases snapped off like twigs from 

 the pressure. After three hours underground the members were 

 not sorry to come to the light again. It was generally supposed 

 that their nearest and dearest friends would not have recognised 

 them in their changed aspect, until water had restored the more 



