﻿Tol. 64.] CAEJBONIFEROUS LIMESTONE OF THE MIDLAND AREA. 



39 



Pig. 2. — Vertical section of the typical 

 Carboniferous-Limestone sequence in the 

 Midland area. 



[The lettering 

 a, b, etc. re- 

 fers to the 

 explanatory 

 table on 

 p. 38.] 



My estimate of the 

 thickness of the cherty- 

 iimestone series is 450 

 feet, as opposed to 

 390 feet given in the 

 Memoir. Some 400 

 feet of this series can 

 be directly measured, 

 upwards from the base, 

 in the hill over Cress- 

 brook Tunnel, and 

 there we do not reach 

 the uppermost beds. 

 Further, the horizon 

 of the upper toadstone 

 is incorrectly given in 

 the Geological-Survey 

 Memoir, the error 

 being due to an in- 

 accurate reading of 

 the stratigraphical re- 

 lations of the cherty 

 limestones and this- 

 toadstone. My con- 

 clusions on this point,^ 

 and the evidence on 

 which they are based, 

 may be stated as fol- 

 lows. At the western 

 end of Litton Tunnel,, 

 cherty limestones are 

 seen to rest conform- 

 ably upon massive 

 white limestones (see 

 explanatory section, 

 fig. 3, p. 40). Westward 

 from the tunnel a slight 

 undulation carries the 

 massive limestones be- 

 low the level of the 



1 Mr. H. H. Arnold- 

 Bemrose, with whom I 

 had the pleasure of exa- 

 mining the ground, agreed 

 with me in the conclusions 

 here stated, and he has 

 summarized them in his 

 recent paper on ' The 

 Toadstones of Derbyshire ^ 

 Quart. Journ. Geol. Soc. 

 vol. Ixiii (1907) p. 244. 



