59 



inferences might be drawn as to the depth of the coal, by com- 

 paring the rocks as they are crossed in succession with sets of 

 specimens of the same collected from the adjoining mines. Data 

 will thus be rapidly accumulated, from which we shall one day be 

 able to infer much better than at present, the extent of certain faults 

 or downthrows, the nature of which can as yet be only imperfectly 

 understood from the evidences produced in the workings of the 

 mines. Nor is it too much to anticipate being able to compute from 

 information thus derived, the depth from the surface of the coal in 

 some places in the interior of the basin. 



To show the constancy of certain layers of rock in particular dis- 

 tricts, and their importance as a guide in particular situations, we 

 may adduce a case given by Professor Phillips of a band of fossilife- 

 rous rock subordinate to a coal field in England. Speaking of a cer- 

 tain seam in the Yorkshire coal field, generally not much more than 

 16 inches in thickness, and traceable from near Leeds to the west 

 of Sheffield, it is stated, " That it would have been impossible to 

 have traced so thin a seam of coal along so extensive a range, 

 without some peculiar facilities, some points of reference more dis- 

 tinct than the varying quality of the coal, and the still more irregu- 

 lar fluctuations of the sandstones and shales. This coal seam is 

 covered by a 'roof unlike that of any other coal bed above the 

 mountain limestone in the British islands ; for, instead of containing 

 only the remains of plants or fresh water shells, it is filled with a 

 considerable diversity of marine shells belonging to the genera Pec- 

 ten and Ammonites, and in one locality, specimens of Orthoceras. 

 The uniform occurrence of these Pectens and Ammonites through 

 so wide a range, over one particular thin bed of coal, and in no other 

 part of the coal strata, is one of the most curious phenomena yet 

 observed, concerning the distribution of organic remains, and will 

 undoubtedly be found of the highest importance in all inferences 

 concerning the circumstances which attended the production of coal." 



We may gather from this the importance of inspecting the sand- 

 stones for fossil remains, should any exist. 



The mining shafts hitherto sunk in this region, have been con- 

 fined exclusively to the vicinity of the eastern and western outcrops, 

 from an apprehension, that more in the interior of the basin, the 

 coal reposes too far from the surface to be readily reached. By fol- 

 lowing the banks of the James river above the mouth of Tuckahoe 

 creek, it will be seen that the coal metals, — that is to say, the sand- 



