With the exception of the very able memoirs drawn out by Sir H. de la Beehe, in the “Geological Survey,” Vol. I, and the sections of the same survey, as compiled by Mr. David Williams, no coal-field has been so little described or worked out as that of the South Wales basin. Although the work of a master geologist, yet the very nature of these memoirs, describing the general arrangements of the rocks in the southwest of England, altogether precludes any attempt at minute geology, which, indeed, should mostly be supplied by local workers. Other coal-fields have been ably and intimately described, but this particular field only in very general terms. Why it should be so I know not, unless it is that only of late years its vast resources have been opened up, and that its many romantic vallies, teeming with beauty above and brimful of coal and mine beneath, have been made accessible either to the tourist or the mining adventurer. Every year, however, sees new railways opened in Monmouthshire and Glamorganshire; and I have little doubt but that the completion of that magnificent work, the Crumlin viaduct, has done more than anything else to attract persons to that part of South Wales, either from a love of the beautiful, or the scientific interest attached to it. For the study of practical geology in its several aspects, this coal-field possesses many advantages, particularly in physical geology and the peculiar manner in which sections are obtained, owing to the nature of the ground.