470 Ruisell Institution. 



quality in different parts. It was first observed by Mr. 

 Whitehurst that under ihis rock no coal is ever tound. This 

 observation Mr. Bakewell said was correct, as applied to 

 workable coal, or such beds that were ot sufficient thickness 

 X,o he got with profit ; but very tliiu seams of coal, as wel} 

 as vegetable impressions, ue not uufrequcnt in these rocks. 

 They extend over a considerable part <>( ihe tiorihern coun- 

 ties, and form the range of central hdls from the north of 

 Derbyshire to Craven in Y-rk^hire, Mr. Bakewell said 

 he was inclined to Ijc'ieve that ihe lower bed, a dark-brown 

 shale, changed its quality as jt passea mto Cheshire, and 

 was there the red sand rock of that and the adjacent 

 counties. He observed that he did not consider some dif- 

 ference in external ch.iracter alone suffieient to disprove the 

 identity of strata which Uiay spread over a larse tract of 

 country. In ihis red sand rock the r lek salt of Cheshire 

 is found. He described the various repositories of salt in 

 Spain and different parts of the world, and observed, that 

 it had l-.e^n found ai the height of 9OOO teet abcn-e the leve! 

 of the sea; and from its position, as well as from the dif- 

 ference of us constituent parts irom those of sea-salt, he 

 vi'as inclined to believe that it had not been formed by the 

 evaporatoin of sea-water, as some geologists have asserted. 

 The rock-salt of Cheshire is remarkably free from im- 

 purities, containing, according to the correct analyses of 

 Dr. Henry, not the least sulphat of magnesia, and not one 

 grain in 1000 of muriate of magnesia. In the same quan- 

 tify of sea salt not less than 46 grains of these two saline 

 impurities occur. 



in the strata over these rocks we meet with beds of coal 

 occupying distinct districts called coal-fields. Mr. B. then 

 described the various kinds of stone-shale, and iron stone, 

 that alternate with coal, and the appearances which oflier 

 indications of its presence. The position into which coal 

 strata are thrown by faults and dykes in different parts of 

 England were exjjlained by drawings and sections. A 

 most siiigular elevation of a bed of coal in the vicinity of 

 the red rock in Lancashire was particularly noticed. Where 

 this rock comes nearly in contact with the coal, the stratum 

 is raised up vertically, whilst seven other beds of coal in 

 the same field are all inclined at an angle of 25 degrees. 

 Mr. Bakewell stated, that he had conununicatcd an account 

 ot this cnal-field lo the Geological Society, as he conceived 

 that it might lead to some discoveries respecting the geo- 

 logical relations of the red sand rock with the coal strata. 

 The obstacles which impede the working of coal-mines 



from 



