classification of certain red clays and sandstones which occur at Walsall Wood. Essington Wood, and at other localities about or within the coal-field. These were at first supposed to belong to the New Red Sandstone, afterwards were believed to be Permian, but are now decided to be true Coal-measures. I find in my own manuscript notes, made during the survey of the coal-field, the strongest expressions of opinion that these were in reality Coal-measures; but as that conclusion involved practical consequences which might, if erroneous, have led some persons into fruitless expenditure, it was thought safer to colour them as Permian until more evidence could be procured.
The opinion that they are upper Coal-measures, however, is now so strongly supported by my colleagues, and by several resident gentlemen of practical experience, and seems so far confirmed by the facts learnt in sinking the pits at Coppy Hall by the Rev. Baily Williams, that there is no longer any necessity for reserve in expressing the opinion, or for hesitation in altering the colouring of the maps and sections accordingly. It adds several square miles to the area of the northern part of the coal-field.
The driving of the tunnel beneath the Rowley Hills, which by a rather unfortunate misnomer is called the Netherton tunnel, added somewhat more of precision to our ideas respecting the "position and lie," of the Rowley basalt than we previously possessed. I regret that I was not aware till it was completed that this so-called Netherton tunnel was being driven through the base of the Rowley Hills, and thus was not led to visit it during the operation. This and the analyses of two specimens of the trap rocks by Mr. Henry, of London, has enabled me to give a little more complete account of the igneous rocks of the district. An equally good analysis of the "green rock" or "greenstone" of the district is still a desideratum.
I regret that an injustice was done in the first edition of this Memoir to the memory of Mr. Keir, whose excellent account of the coal-field, so far as it was known in his day, was published in Shaw's History of Staffordshire. Not only were his labours altogether ignored, but some of his materials were used at second hand without any acknowledgement of the true source whence they
