570 Notices from the Minute Books of the Geological Society. 



wealth, except that the sandstones and shales displayed on the surface belong to 

 the carboniferous measures. That the district is affected by faults, may be inferred 

 from the repetition of beds identical in mineral character, and the amount of the 

 presumed dislocations may be easily ascertained. In this instance the value of the 

 seams of coal, which trials may have proved, is less affected than in No. 4, and the 

 probable produce, in the direction of the strike, may be estimated. The depth at 

 which the same bed may be found between the lines of fault is also readily deter- 

 mined, and the working of the coal resumed, should the calculated produce justify 

 the undertaking. The true nature of the district is exposed on the sides of the 

 model, and the complication of the interior, in a plane oblique to the horizon, is 

 shown by removing the upper part. 



6. This model exhibits some of the phsenomena of the intersection of veins ; 

 also the different relative levels of the surface of a dislocated bed of coal. Mr. Sop- 

 with, in his description of the models, considers the white vein as marking the 

 first dislocation, whereby the relative displacement of 4 and 3 with reference to 



1 and 2 was effected; 2 by that movement not having been detached from 1, 

 but continued on the same level, nor 3 from 4 ; and it will be easily perceived that 

 if 2 and 1 be, in imagination, placed on the same plane, 3 and 4 will likewise con- 

 stitute a continuous plane at a certain lower level : by a subsequent dislocation, 

 marked by the brown vein, 1 and 4 are supposed to have been upcast, or 2 and 3 

 thrown down, 1 and 4 preserving their former relative positions as well as 2 and 3. 

 Two dislocations therefore produced 4 different levels. In consequence of the inter- 

 secting cracks or veins not being perpendicular to the horizon, there is an apparent 

 lateral shift at the point of intersection, not only in the veins, but in the portions 



2 and 3 of the coal-bed. The phsenomena dependent on the structure of the model 

 are exhibited as usual by the sides and by an oblique intersection, and Mr. Sop- 

 with points out the means by which the relative antiquity of intersecting veins 

 may be determined. 



7. In this model the effects of denudation on No. 5. are shown, the angular irre- 

 gularities produced by the dislocations being rounded off, and the physical outline 

 giving no indication of the disturbances. On a comparison of the two models, the 

 same description of displaced plans will be found in each. In No. 7, Mr. Sop- 

 with has introduced a groove which traverses the upper part of the model, and is 

 supposed to represent the boundary of an estate. By referring to the back of the 

 model, it will be perceived that the groove is carried down perpendicularly, defining 

 underground the limits of two estates ; it will also be perceived that the white 

 vein is intersected by it, and consequently the right of working the vein possessed 

 by the owner of the property in which it appears on the surface would cease at the 

 line of intersection. 



