COAL-FIELD OF CLACKMANNANSHIRE. 143 



of alluvial cover, which completely hides the crop 

 or outburst of the strata, termed generally by mi- 

 ners the Rock-head, from our view, and also com- 

 pletely hides the fissures, dikes and dislocations 

 of the strata, which produce such material altera- 

 tions in the coal-fields, and which are frequently the 

 occasion of great loss to the mining adventurer. 

 The alluvial cover is to the strata which exist un- 

 derneath, as the flesh upon the bones in animals : 

 if the flesh is removed, the whole structure of the 

 bones, their situation and connection, are at once 

 discovered ; in the same manner, were the alluvial 

 covering removed, the whole strata would be dis- 

 tinctly seen, and the effect of every dislocation im- 

 mediately ascertained. Though the total removal 

 of the alluvial cover might, in one view, appear to 

 be of great advantage, in affording facility in 

 ascertaining the strata existing in any district, yet 

 this advantage w T ould be greatly outweighed by 

 the disadvantages, not only in the want of soil 

 for cultivation, but by the strata being denuded, 

 the coal-mines would be deluged with water every 

 rainy season, whereas the alluvial cover affords pro- 

 tection, by causing the water to flow along the sur- 

 face till it join the rivers, which are the great na- 

 tural drains for the water on the surface of the 

 earth. 



The absolute shape of the coal-fields in Great 

 Britain, has been ascertained with a precision 

 beyond that of any other mines in the globe, and 



