560 Prof. Dr. J. S. Neicherry — On " Cone-in- Cone J' 



the Geological Society of Glasgow, in wliicli he advances the theory 

 that this peculiar structure is caused by the escape of gases. 



"While I was yet a boy I found cone-in-cone, and was puzzled 

 by it, but examining a fine exposure of it in which the bases of 

 the cones were all turned upward, the theory of escaping gases 

 suggested itself to me. Subsequently, when I was a student in 

 the Jardin des Plantes, Paris, attending the geological lectures of 

 M. Cordier, he described cone-in-cone as an imperfect crystallization. 

 I proposed to him the theory of the escape of gases through a pasty 

 medium, but he said that would not do, because the points of the 

 cones were sometimes turned upward, sometimes downward. This 

 led me to review the subject later, and while I had the supervision 

 of the Geological Survey of Ohio, and was connected with tlie 

 Government Surveys in the Western Territories, I had opportunities 

 of observing the occun-ence of cone-in-cone in a large number of 

 localities, and at many geological levels. The results of my obser- 

 vations are given in the Eeport of the Geological Survey of Ohio, 

 Yol. I. p. 211. They are briefly as follows : 



Cone-in-cone consists, as is well known, of a series of hollow 

 cones like extinguishers placed one within another, and it some- 

 times makes up the entire mass of a stratum several inches in 

 thickness and many feet in lateral extent. It is not confined to 

 one horizon, but occurs throughout the geological series wherever 

 there are argillaceous shales, locally impregnated with lime, or in 

 which septaria or clay-iron-stones are found. More generally the 

 cone-in-cone structure is observable in lenticular sheets of earthy 

 limestone or shale impregnated with lime, and in each sheet the 

 cones are usually turned in the same direction, oftenest with the 

 points down, but sometimes turned upward, and occasionally turned 

 in both directions. In one locality in Ohio where cone-in-cone 

 occurs abundantly in the Waverley shales (Lower Carboniferous), 

 a lenticular mass is divided obliquely by a sheet of clay-iron-stone. 

 On one side of this the points are turned downward, on the other 

 side they occupy a reversed position. I have before me as I write 

 a nodule of iron ore from the same locality which is surrounded by 

 cone-in-cone two inches in thickness ; the cones above are turned 

 point downward, those below point upward, and those on the sides, 

 somewhat confused by pressure, are divergent. 



In the Cretaceous formation of Colorado lime concretions occur 

 with a radiated cone-in-cone structure, and similar concretions are 

 reported by Dr. C. A. White in the Coal-measures of Iowa (Amer. 

 Journ. Science, vol. xlv. 1868, p. 401). Again, in the Huron 

 Shale (Upper Devonian) of Ohio, the bones of the great fishes 

 (DinicJithys) are generally coated with a sheet of impure limestone 

 which has cone-in-cone structure ; and here the cones are divergent 

 from the surfaces of the bones, however irregular these may be. 



Such specimens as these I have described seem to me to be in- 

 compatible 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. 



