146 COAL-FIELD OF CLACKMANNANSHIRE. 



of coal in each of the coal-fields, marked a a. At 

 the same time, all the coals, and all the very nu- 

 merous accompanying strata, lie exactly in the 

 same situation. This plan represents the Ochill 

 Mountains, with the north coal-field, of a long el- 

 liptical bason-shape, the side next the mountains; 

 being very steep, and the south, the east and west 

 edges of the bason shelving out at a great distance 

 from the lower part of the bason, which is termed 

 by miners the Trough. It is therefore evident; that 

 the coals and accompanying strata in the north coal- 

 field, dip in every direction to the line of the 

 trough. The middle coal-field, which is formed by 

 the great north slip, is only the segment of an el- 

 liptical bason, as represented in the plan^ where the 

 strata dip in every direction to the middle mark- 

 ed x, being the deepest part of the segment. The 

 south coal-field formed by the great south slip, is 

 also the segment of another elliptical bason, similar 

 in all respects to the middle coal-field. Beyond the 

 crop of the coals and strata of the south coal-field, 

 the counter dip of the strata takes place, producing 

 the mantle-shaped form, which causes the coals in the 

 Dunmore coal-field in Stirlingshire, to lie in a direc- 

 tion directly contrary to the coals and accompany- 

 ing strata of the south coal-field of Clackmannan- 

 shire. 1 . 



In order, however, to represent the effects of 

 dikes, great slips lying in the line of bearing of the 

 strata, and of the slips or dislocations in an oblique 



