60 
THE GEOLOGIST. 
brokeshire coal-field, as both differing a good deal from the other in 
arrangement of beds and quality of coal, and separated from it by a 
considerable interval of old red sandstone. 
The basin is bounded on the north, east, and west by a pretty 
uniform belt of millstone grit and mountain limestone, and on the south 
by a rather intricate interlacement of old red, mountain limestone, 
permian, and lias. The greatest depth is stated to be near Neath, where 
the lowest strata are 700 fathoms below the outcrop of the upper ones 
in the hilly districts. The physical features are pretty much the same 
throughout the country, although the quality of coal varies exceedingly, 
it being on the Monmouthshire or north-east side of a good coking kind, 
while below Merthyr, and in the Glamorganshire vallies, it has taken the 
character of stone coal. The coal in the Aberdare valley has been taken in 
large quantities down to Cardiff, as being of the best and cleanest kind for 
the use of the steamers. Having furnished this general outline, let us 
look more closely at this district in particular. Like all the rest of the 
field, the country is here divided into a great many narrow parallel 
vallies, which run from the north belt of limestone towards the sea, 
and are separated from each other by long mountain ridges. If we 
ascend one of these ridges, say the Doman Vawr, between Ebbw Vale 
and Nantyglo, we shall see as fine an example of physical geology and 
beautiful scenery as can be well imagined. To the north is extended 
the dreary table-land of millstone grit, succeeded by the limestone 
escarpments of the Llangynider range ; while, beyond them, are the 
old red sandstone mountains of the Daren and Penallt Mawr, from 
whence, in heavy prominence, stands out the isolated mass of grit and 
limestone of Pen Cerrig Caleb. To the east are seen the outlines of 
the Sugar Loaf and Skyrrid, capped by their old red conglomerates, 
while in the interval between them are the far distant peaks of the 
Plutonic Malverns. To the west, peering over their humbler neigh- 
bours, are the Breconshire Beacons (2,862 feet), keeping grim watch 
over the old town of Brecon and the Vale of Usk, while still to the west 
the eye can trace the same bold outlines of the northern border running 
into Carmarthenshire. To the south glistens the Bristol Channel, 
backed up by the faint Mendips and the Devonian coasts of Minehead 
and Ilfracombe ; while, from east to west, appear ridge after ridge of 
Pennant sandstone like waves of a large sea, only distinguishable from 
each other by the alternations of light and shade and the masses of 
