PREFACE TO THE SECOND EDITION.
It was not till the month of October 1858 that I could make arrangements for such a re-examination of the South Staffordshire Coal-field as should enable me to bring out a second edition of this Memoir. Many new mines and cuttings of different kinds having been opened during the preceding nine years, this re-examination, brief as it was, afforded fresh information on some points that had previously been obscure.
My colleagues, Messrs. Hull and Howell, under the direction of Professor Ramsay, have completed the examination of the details of the New Red Sandstone of the Midland counties, and Professor Ramsay has now contributed (pp. 3 to 8) an account of their results.
I have added also to the description of the Permian rocks an abstract of Professor Ramsay's remarkable speculations on the origin of the large angular blocks in the Permian breccia (pp. 13 to 15).
In the coal-field, the new pits at Essington and those on Cannock Chase gave additional data for the co-relation of the Wyrley and Essington district with the remainder of the field. The identity of the separated coals of Wyrley and Essington, (from the Old Robins coal down to the Bentley Hay coal), with those which, in the central part of the coal-field, unite to produce the Thick coal, is thus put beyond doubt. There was, indeed, no doubt on my own mind of this fact even ten years ago. A diagram, illustrative of the method of this expansion of the measures and separation of the coals, is now added to the general description of the Coal-measures.
An important change has been made, both in the Memoir and in the latest edition of the maps and sections, as regards the
