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clear distinction between the upper or thicker measures, which contain the ten- 

 yard coal, generally known as the Dudley coal, and the underlying carbonaceous 

 strata, or ironstone measures. The latter, rising from beneath the ten-yard coal, 

 range to the N.N.E. from Wednesbury and Bilston, in a long tract between the 

 parallels of Walsall and Wolverhampton, extending to Cannock Chace. At the 

 southern end of the field, emerging from beneath the ten-yard coal, they occupy 

 the district between Stourbridge and Hales Owen, containing the well-known 

 " fire clay ;" though some of the most valuable of the Wolverhampton iron-stones, 

 beneath those called the " New Mine," are here wanting, viz. the " Gubbins," 

 and " Blue Flats." This poverty in the lower coal measures extends over all the 

 district south of Dudley. In the northern and southern end of the district, these 

 lower measures represent the whole carboniferous system ; and in various natural 

 sections near the Hagley and Clent hills, the author has detected them, in very 

 feeble bands, passing upwards and conformably into the lower new red sandstone. 

 Besides the open works formerly alluded to by him in previous memoirs, Mr. M. 

 now states, that his former conjectures respecting the passage of the ten-yard coal 

 beneath the new red sandstone which flanks it on the east and west, have been 

 verified by the efforts of the Earl of Dartmouth, who, after sinking to a depth of 

 151 yards through strata of the lower new red sandstone, has very recently suc- 

 ceeded by further borings, carried down to the depth of 290 yards, in discovering 

 the one-foot, two-foot, and " Brooch" coal seams, which overlie the ten-yard coal 

 throughout the Dudley field. These operations have taken place at Christchurch, 

 one mile beyond the superficial boundary of the coal field. 



Besides the plants so common in all carboniferous tracts, the author has ob- 

 served the presence of animal organic remains. Unio3 of several species are 

 abundant ; and in the northern or lower part of the field he has extracted frag- 

 ments of fishes, which have been named by Professor Agassiz, Megalichihys 

 Hibbertii, M. Sauroides, and Diptodus gibbus ; together with scales, coprolites, 

 &c, proving an identity between the animals deposited in these coal measures and 

 those of Edinburgh, described by Dr. Hibbert. The same species, it will be 

 recollected, have been pointed out by Sir Philip Egerton, as occurring in the N. 

 Staffordshire coal-field, and one of them has been observed by Mr. Prestwich in 

 the coal-field of Coalbrook Dale. Mr. Murchison, however, remarks that he has 

 not yet observed any marine remains in these coal measures similar to those of 

 Coalbrook Dale ; and nothing yet found can invalidate the inference that the coal 

 of Dudley and Wolverhampton may have been accumulated exclusively in fresh 

 water, 



b. Silurian rocks. — The mountain or carboniferous limestone and the old red 

 sandstone, which in so many other parts of England form the support of coal tracts, 

 being wanting, this field reposes directly on rocks which Mr. Murchison proves to 

 consist of the two upper members of the Silurian system, viz., the " Ludlow 



