50 



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 I^eath, 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. Haying 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 Yale 

 and [NTantyglo, 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 Yale 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 shndo and the masses of 



