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'oducing two principal systems of 
fissures, which intersect at nearly right angles. The effect of the N.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 haematite 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 rook, to an extent, 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 
considei'ed a " formation," more especially if this word be considered 
equivalent to "period." The surpi'ise, 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 
