FACTS AND INFERENCES. 2.91 



It may be proper to notice, however, that some of the strata, 

 after behig discontinued, are found, in several instances, to resume 

 tbeir stations. Thus, the upper shale, which is wanting- in Lincoln- 

 shire, reappears in the gault of Cambridgeshire, and perhaps in the 

 hlue marl of Folkstone, which is continued on the opposite coast of 

 France.* Yet our upper shale, as was formerly observed (p. 60), is 

 so like the London clay, that had it occurred above the chalk, it would 

 doubtless have received that appellation. Indeed, as the green sand 

 is found under the chalk in some places, and above it in others,t the 

 position of the clay may admit of the same variation. 



In some parts of Somersetshire and Dorsetshire, the chalk comes 

 in contact with the red sandstone, all the intervening strata having 

 disappeared; but in other parts of that district, the series bears a con- 

 siderable analogy to ours; there being an upper shale (termed Oak- 

 tree clay ), some oolite and sandstone strata, aluminous or lias strata, 

 and red sandstone. It would seem also, that our second shale occurs 

 in some spots, under the designation of clunch clay. There are, how- 

 ever, few places where this analogy is distinctly seen; and when we 

 attempt to trace it out of Britain, and especially out of Europe, we 

 soon find ourselves completely lost. 



10. Some parts of the strata are so nearly allied, that they often 

 pass into one another, and occupy the same beds. — This observation 

 applies particularly to sandstone and sandy shale, to coal and bi- 

 tuminous shale; and, we may add, to oolite and grey limestone; 

 which, as we have observed (p. 270), pass into one another, at Kn-k- 

 dale and other places. — Here it may be also remarked, that in other 

 respects, the qualities of beds are liable to great changes and transi- 

 tions. The dogger is perhaps the most variable of all our rocks; but 



■* Geological Tiansactions, III. p. 343; V. p. 37, 49. 

 t Greenough's Geology, p. 255. This Work contains a most valuable collection of facts, 

 many of vhieh serve to illustrate and confirm our statements. 



