280 



TRANSACTIONS OF THE 



shaft sections of the two coal veins on opposite sides of 

 the basin, and carefully following up the examination of 

 the intermediate stratification, little hesitation can be en- 

 tertained of their perfect identity and continuity. In 

 each section, (and several others resembling them might 

 have been added) the upper vein, which is also the 

 thickest, consists of the best quality of coal, while the 

 lower vein is comparatively inferior and depreciated by 

 sulphuret of iron. 



We have further evidence of the continuity of the 

 carboniferous strata, in the perfect accordance in their 

 component structure, particularly the remarkable, thick 

 series of micacious grits and conglomerates. To this 

 may be added the testimony of the only species of fossil 

 plant, a peculiar variety of calamite; which at Chester- 

 field pits occurs at the depth of 320 feet, or 60 feet 

 above the coal, and in a similar position at Anderson's 

 or Graham's deep mine on the opposite side of the 

 basin.* 



It will not be necessary to occupy space by recapitu- 

 lating the details of the numerous beds, measures or 

 metals, passed through in our principal sectiop of the 

 deep shaft, pi. 16, fig. 5, to which the reader is referred. 



A classification of these beds furnishes the following 

 result. 



Forty beds, coming under the denomination of carbo- 

 niferous, gritty, micacious, or argillaceous shales, com- 

 prise a total thickness of 134 feet. 



Fifty-one beds, consisting of white and grey micacious 

 grits, some of them fine, others approaching to the 

 character of conglomerates, yet containing feldspar crys- 

 tals like porphyry, amount in the aggregate to 267 feet. 



* In elucidation of the relative positions indicated above, it may be stated, 

 that the Chesterfield mines, represented in pi. 16, fig. 4 and 5, Graham's pits, 

 at fig. 1, and Willis's and Crouche's pits, fig. 2, occupy the three points of a 

 triangle, about ten miles apart from each othei-. 



