248 



THE GEOLOGIST. 



accordingly, we find great lines of fault on the south-western sea- 

 board, and inland to the edge of the coal-basin in Glamorganshire, 

 running N.W. and S.W., and pi\)ducing two principal systems of 

 fissures, which intersect at nearly right angles. The effect of theN.W. 

 fractures has been, mainly, to thrust up the strata into dome-shaped 

 protrusions ; and it is probable that these disturbances were of more 

 ancient date than those which produced the undulating character of 

 country, and which forced up the rocks in east and west directions, 

 originating at the same time a parallel system of faults. It is in con- 

 nexion with this series of east and west fissures that we must look for 

 the origin of the deposits of hsematite at Llantrissant and Newton 

 Nottage. 



The most important workings of the hsematite-ore in the Llantris- 

 sant district, are probably those of Mr. Vaughan, at Cornel Park, and 

 the adjoining Hendy Mine, on the lands of the Marquis of Bute. 

 Both mines are worked " open-cast " — that is to say, the super- 

 incumbent strata are stripped from the upper surface of the vein, 

 which is then worked through its whole thickness after the manner of 

 a quarry. This is probably the most ancient mode of mining, and 

 in countries where the " old men " have been, the magnitude of the 

 excavations often affords a rude proof of the former wealth of the 

 neighbourhood, as well as indicates the value of the deposits likely 

 to be encountered by continued exploring. But to the geologist these 

 open-cast workings possess the greatest advantages, since they reveal 

 those details of structure and association, both in regard to the depo- 

 sits themselves as well as to the containing rock, to an estent, and 

 with an amount of convenience to the observer, which can seldom or 

 never happen in subterranean mines. In both geologist and miner 

 the workings in the vein of ore at Cornel Park must provoke a sense 

 of wonder. Indeed they cannot fail to set the former speculating upon 

 the origin and segregation of such enormous quantities of a particular 

 mineral, which, by its mass and constancy of position, here becomes, 

 stratigraphically speaking, almost entitled to the dignity of being 

 considered a " formation," more especially if this word be considered 

 equivalent to "period." The surprise, too, of the intelligent miner, 

 in connexion with the experience of his profession, must be very 

 great, since, in this case, we have the rare occurrence of a bed of 



