376 



TRANSACTIONS OF THE 



as in Huel Alfred and the Weeth mines. They are also 

 crossed by slides. 



The cross flukans form the seventh class. They vary 

 in width, from the smallest imaginable size to 9 feet : 

 their average width may be stated at 1 foot. However 

 small they may be, no water can percolate through them. 

 Their general direction is nearly north and south, and 

 underlying toward the east. 



The eighth class is composed of the slides, probably 

 the last of the true veins, being found to traverse veins 

 of every other kind ; they are composed wholly of clay, 

 which is generally of a more slimy nature than is often 

 found in other veins. They run in all directions ; but 

 their general direction is nearly parallel with that of the 

 tin and copper lodes. Instead, therefore, of heaving 

 them longitudinally, as the cross veins do, they appear 

 either to throw them down or throw them up : the for- 

 mer, when they underlie in the same direction as the 

 lodes ; the latter, when in an opposite direction. 



These veins are generally very small, seldom more than 

 one foot wide; and they usually underlie very fast, which 

 indeed is probably the reason of their being called slides ; 

 or perhaps because, when they underlie in the same di- 

 rection as the lodes, the latter, on meeting them, appear 

 to slide downwards. 



Thus, then, have been described the various periods 

 or ages of the different kinds of veins with which miners 

 are acquainted. The details drawn from different data 

 present many startling facts ; and demonstrate clearly, 

 in whatever manner they may have originated, that the 

 power which was exerted, acted at lengthened intervals 

 of time. It is a view pregnant with strong interest to 

 geologists, and it is to be hoped that, in after times, such 

 'further light may be thrown on the subject as may tend 

 to elucidate much that is now mysterious in the past 

 operations of nature. 



