W. S. Gresley—On " Cone-in- Cone'' Structure. 17 



flexures in them, every section almost, of a few yards in length, 

 afibrding an indication of disturbance. 



Between Clovelly and Portledge Mouth the Upper Culm Measures 

 consist of grey, lilac-grey and reddish thick-bedded even grits, with 

 interstratification of dark grey shale. The even-bedded character of 

 this series renders the flexures in the cliff's very apparent, especially 

 when dark grey shale bands are affected by them, as at 31 chains 



from Clovelly Pier where sharp 



^^^- ^- inverted curves are shown, V 



shaped flexures are visible about 



14 chains from the Pier, and from 



18 to 22 chains from the Pier the 



beds are contorted and faulted. 



At about 70 chains from Clovelly 



beautiful examples of marine tun- 



( V nelling are aff'orded by the Black 



Church rock, in which two tunnels 



have been excavated along the bedding, and by a neighbouring I'eef 



in which the sea attacked the opposing strike surface, the tunnel 



being roofed by a massive bed dipping landward. 



To enter more fully into the many inverted and ordinary curves 

 exposed in this interesting coast would be beyond the purport of 

 this paper, I have not attempted to give a digest of the numerous 

 notes I have made of the Culm Measure area, nor do I think it 

 would be possible to do so ; but I trust that I may have succeeded in 

 directing attention to a large district practically unknown to geolo- 

 gists, and in showing that, in spite of the confusing complexity of 

 detail, it is possible to obtain something like a definite sequence. To 

 make out the structure thoroughly would require years of patient 

 labour on the 6 inch scale, and is in no sense feasible in holiday 

 rambles ; but there are curious structural phenomena which would 

 amply repay the labours of the casual visitor. 



III. — Notes on " Cone-in-Cone " Structure. 

 By W. S. Gresley, F.G.S. 



IN Decade III. Vol. II. of the Geological Magazine, for 1885, 

 at page 283, an abstract of a paper on " Cone-in-Cone "by Mr. 

 John Young, F.G.S., of Glasgow, was given. The author of this 

 interesting paper has kindly presented the writer with a copy of it, 

 to which, since it was read in Glasgow last year, has been added 

 some additional remarks, together with two very beautiful plates, 

 by ' photogravure,' in illustration of some of his typical Scottish 

 specimens. 



The result of Mr. Young's labours in this connection have 

 warranted him in arriving at the following conclusion respecting 

 the origin and formation of cone-in -cone structure, which, briefly 

 stated, is this : — That the formation is due to the " upward and suc- 

 cessive escape of gases generated in the lower portion of the 

 stratum in which the structure is found, probably by the decay of 



DECADE III. VOL. IV. NO. I. 2 



