GEOLOGY OP DERBYSHIRE. 233 



pletely conveying the idea of the limestone having been deposited 

 on the rough uneven surface of what must have been at that time 

 solid toadstone, and which has since decomposed into clay. The 

 toadstone has undoubtedly not been injected into the limestone, but 

 poured out as a lava current on the bed of the ocean in which the 

 mountain limestone was deposited. 



We now come to the important question of the number of parts 

 into which the mountain limestone is divided by the toadstone, or, 

 in other words, the number of the beds of toadstone existing in this 

 formation. Farey and the old geologists, in examining the country, 

 found the toadstone bassetting or coming out to the surface in many 

 places, in the sides of valleys or at the tops of hills, and finally 

 agreed that there were three distinct beds, separated from each 

 other by two beds of limestone, and having limestone above and 

 below them ; thus making four limestone and three toadstone beds. 

 Mr. Hopkins, however, of St. Peter's College, Cambridge, after a 

 very laborious examination of the district, has shewn (in a pamphlet 

 to which, I am sorry to say, I cannot refer my readers, as it was 

 only printed for private circulation) that this conclusion is by no 

 means warranted by the facts of the case ; but that these, when 

 thoroughly investigated and followed out into all their consequences, 

 prove the existence of only one known toadstone bed over by far the 

 greater portion of the district. This one bed, together with the 

 limestone above and below it, is so fractured by faults in different 

 directions, as to have different portions of it brought up in various 

 places, thus producing the deceptive appearance of several beds. 

 Since Mr. Hopkins's examination of the country, however, it has 

 been proved, by sinkings in one perpendicular shaft, that over a part 

 of the district there are two beds of toadstone, as the following sec. 

 tions show :— 



Wheals Rake Mine. 



1st Limestone 57 feet 



1st Toadstone 84 



2nd Limestone 48 



2nd Toadstone 9 and more. 



The thickness of the second toadstone here is unknown, as the 

 workings have not been continued to a greater depth. 



VOL. VIII., no. xxiv. 30 



