622 



E. Wilson — Sections in Tideswell Dale. 



"The entire section exposed would thus be about 31ft. The 

 columns, if exposed for some time to the atmosphere, weather to a 

 colour similar to that of the toad stone (rusty iron with green 

 blotches). The unweathered toadstone is here a dull olive green. 

 The red clay mass is undoubtedly the continuation of that oc- 

 curring in the previous section (Fig. 1), and I have proved, by 



Thickness, 

 ft. in. 

 16 6' exposed to surface. 



2a— 



^ III < ji" ^ 



• PragBtents of columns 

 broken off and fallen down. 



J 



31 2 



6 exposed. 



Fig. 2. Section in Quarry, Tideswell Dale, Derbyshire. 

 (Explanation of figures same as in Section, Fig. 1, p. 521.) 



finding fragmental columns in other portions of the Dale, that its 

 development is coextensive with the toadstone in this locality. I am 

 aware that there is an upper claij (?) band not represented in this 

 district also in connexion with the toadstone ; but I am not aware 

 of any locality where these clay-bands are present and the toadstone 

 wanting. I noticed that there were no clay partings in the lime- 

 stone, though we do occasionally find thin clay partings in it; 

 the thickest that I have ever heard of is only 8 inches, or not 

 one-tenth the thickness of this clay band. There is, besides, no 

 intermixture of shales, false bedding, or other impurity or irregu- 

 larity in the strata, as in the more littoral South Derbyshire equiva- 

 lents of the upper part of this formation ; nor should we expect 

 this, as in the neighbourhood of the High Tor, Derbyshire, the 

 highest toadstone is covered by 150 feet of almost pure limestone, 

 indicating the continuation of deep sea conditions for a considerable 

 period after the formation of this clay (?)-bed." 



Without entering more into details at present, I will select two quo- 

 tations from Lyell, as bearing on this subject, contained in my paper : 



"At the summit of the I. of Cyclops a mass of stratified clay 

 with occasional arenaceous lamina rests on (intrusive) columnar lava. 

 In some places the overlying clay has been greatly altered and 

 hardened by the igneous rock, and occasionally contorted^ hut the lamina- 

 tion is rendered more conspicuous.^' 



