Correspondence — Mr. John Young. 139 



COKBESPOUIDElsrGE. 



« CONE-IN-CONE." 



Sir, — I am glad to observe in the short article on "Cone-in-cone," 

 by Professor Newberry, M.D., in the December Number of the 

 Geological Magazine for 1885, that he at one time was inclined to 

 look upon that structure as due to " the escape of gases through 

 a pasty medium." I think that if he had the opportunity of studying 

 the large series of specimens that I have now assembled, and the 

 transparent sections of the cone structure that I have prepared, he 

 would still be inclined to favour that view as an explanation of the 

 phenomena that they present, rather than the one he now adopts, 

 viz. " an imperfect crystallization " of the deposit in which it is 

 found. Professor Newberry, after referring to a number of cases 

 of cone-in-cone structure that had come under his observation (some 

 of which apparently differ from what I have described), concludes 

 by stating that these examples " seem to me to be incompatible with 

 the theory that cone-in-cone is caused by pressure, or the escape of 

 gases, and appear rather to confirm the conclusion that it is due 

 to an impeded tendency to crystallization." He, however, in the 

 article in question, offers no evidence in support of this crystallization 

 theory, nor does he explain in any way the peculiar structure and 

 arrangement of the cone layers. Those supporting a crystallization 

 theory have not referred to any known law of crystallization, which 

 would account for a structure agreeing with what is seen in the best- 

 preserved specimens of our Scottish cone-in-cone, or which would 

 satisfactorily explain all that is represented in the external structure 

 of the cones, and their terminations on the surface of the bed, as is 

 briefly noted in the short abstract of the paper I read to our Glasgow 

 Geol. Soc, and printed in the June Number of the Geol. Mag. 

 for 1885. In the abstract, to which 1 would refer your readers, 

 I have endeavoured to indicate what is seen in both the internal and 

 external structure of the cones, but which I explain more fully in 

 my paper, and T do not think that in either I have ventured 

 to hazard any explanation that is not fully warranted by what 

 the specimens reveal. 



During the progress of my investigations, I have not wholly 

 relied upon my own judgment in coming to the conclusion that the 

 cone-in-cone structure was due to the escape of gases generated in 

 the sediment, but that from time to time I have had the opportunity 

 of submitting specimens and sections of the structure to Dr. Young, 

 Prof, of Geology ; Prof. Sir William Thomson, President of the 

 Glasgow Geol. Soc, and his brother Prof. James Thomson, who has 

 paid some attention to rock structures; likewise to Mr. Ferguson, 

 Prof, of Chemistry in this University, and to others, on whose 

 opinion I could rely, and I am pleased to be able to state, that they 

 are all inclined — so far as the specimens noticed in my paper are 

 concerned — to agree to the explanation I have given as to the pro- 

 bable origin of the structure. They also agree with me in thinking 

 that none of the agencies to which cone-in-cone structure has been 



