112 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 9, 



including angular fragments of the shale, some beds of which on this 

 side are very tender and cleave readily into rhomboidal pieces. The 

 coal enveloping these fragments must have been softened sufficiently 

 to allow them to penetrate it, but it has more numerous and less 

 regular di^dsional planes than in the central parts of the mass, and 

 has probably been shifted or crushed somewhat, either when it re- 

 ceived the included fragments or subsequently. Both at the roof and 

 floor, the coal shows distinct evidence of a former pasty or fluid con- 

 dition, in having injected a pure coaly 

 Fig. 4. Relation of the ''Albert substance into the most minute fis- 

 Coar to the containing beds, g^j,gg ^f ji^g containing rocks. On 

 as seen near the shaft of the ij^^i^ ^.Q^f ^nd floor also, but espe- 

 cially the latter, there are abundant 

 evidences of shifting and disturbance 

 in the slickenside surfaces with which 

 they abound. All these appearances 

 I have endeavoured to represent in 

 fig. 4, which agrees in the essential 

 points with a similar figure given 

 by Prof. Taylor, who does not, how- 

 ever, represent the contorted state of the beds and the crushing of the 

 lower side of the coal. 



The levels of the mine extend on both sides of the shaft along the 

 course of the coal. On the south-west they extend about 170 feet, 

 when the coal narrows to a thickness of one foot. In this direction, 

 however, I had not time to examine them. In proceeding to the 

 N.E., the coal has a general course of N. 50° E,, bending gradually to 

 N. 65° E., and everywhere presenting the appearances already noticed, 

 though attaining, in one place, a width of 13 feet. At the distance 

 of about 200 feet from the shaft, a remarkable disturbance occurs. 

 The main body of the coal bends suddenly to the northward, its 

 course becoming N. 29° E.* for about 25 feet, when it returns to a 

 course of N. 50° E. At the bend to the northward, a small part of 

 the vein proceeds in its original course, and is stated by the persons 

 connected with the mine to run out, leaving a large irregular pro- 

 montory of rock between it and the main body of the coal. This 

 disturbance has been variously represented as a fault, and as a cutting 

 of the vein across the strata. Though I confess that the appearances 

 are of a puzzling character, and are but imperfectly exposed in the 

 mine, the impression left on my mind is that it is, on a large scale, a 

 flexure similar to that represented in fig. 3, and accompanied by a 

 partial tearing asunder of the beds. It seems evident that the beds 

 must have been in a soft state at the time when this disturbance 

 occurred, although there may have been subsequently some vertical 

 shifting, especially on the west side of this " Jog." 



Beyond this flexure, the deposit contracts in width, and becomes 

 more regular, and eventually its containing walls assume a conforra- 



* These measurements were made with a pocket prismatic compass. They 

 differ slightly from those of Dr. Jackson, either from accidental circumstances, or 

 from beino; taken in different levels of the mine. 



