210 W. A. Tarr — C one-in-C one. 



parallel to these radiating fibers is compatible with this 

 suggestion. Giimbel has made an interesting suggestion 

 along these lines. He thinks that water might find its 

 way through a bed and form stalactites on the under side, 

 each stalactite having a cone shape. 



It should be noted that the most perfect cones are 

 always developed in radiating aggregates of fibers. 

 When the fibers are parallel the peculiar cone with a 

 flaring base and a long slender body develops. 



It is very probable that those who have expressed the 

 view that cone-in-cone was due to crystallization were 

 thinking of radial aggregates as the initial cause of the 

 conical form. Such radial aggregates may be seen in 

 concretions. And it cannot be said that crystallization 

 might not form aggregates which would be the real cause 

 of the cone-in-cone structure. Such a radial aggregate 

 would provide the form, without resorting to cleavage as 

 a factor in initiating movement in the cone-in-cone. 



Aside from the possibility of the influence of radial 

 fibrous aggregates and the cleavage of aragonite, both of 

 which would influence the initiation of the cone-in-cone 

 while the material was still aragonite, there are two other 

 suggestions as to the origin of the conical form that are 

 of value. One is dependent upon pressure and the other 

 upon the alteration of the aragonite to calcite. 



That pressure alone might produce cones was suggested 

 to the writer as the result of testing some cubes of lime- 

 stone to determine its crushing strength. Perfect and 

 imperfect cones were formed during the tests, the largest 

 ones being two inches across the base. Many were 

 remarkably perfect and showed several features seen in 

 the cone-in-cone. The included angle at the apex of the 

 cone was from 30° to 60° and in some cones the angle 

 was greater near the base than at the apex, a feature 

 noted in some cone-in-cone. In the mechanical produc- 

 tion of cones there also may be seen an explanation of 

 cone-in-cone structure, because, on the base of the larger 

 cones mentioned above, there were numerous minute cir- 

 cular cracks, which indicated that another cone might 

 develop within the first. When the fibers of the calcite 

 are radial, pressure upon the base of such a group might 

 easily induce a fracture, more or less parallel to the fibers, 

 which would be circular. Thus the outline of the cone 

 would be inaugurated. Solution along this fracture 



