734 ME. W. S. GRESLEY ON CONE-IN-CONE IN THE [Nov. 1 894, 



surrounding shales. Upon the layer of stone are two separated 

 cakes of cones on the same plane — one above the watch, the other 

 over the dark cavity below the core or nucleus. Above and between 

 these two cone-patches is a layer of shale. Over this comes a well- 

 developed layer of cones, then another shale-layer, and above that the 

 third height of cones, which thins out before it reaches the edges of 

 the underlying conic layer. Just beneath the core or nucleus, and 

 level with the bottom of the watch, the inverted conic layer occurs, 

 as the figure more or less clearly shows. 



No two conic masses appear to be alike ; not only do the size, 

 position, thickness, perfection, and number of the overlying and the 

 underlying (ordinary and inverted) conic cakes vary extremely, but 

 the entire structure — the tout ensemble of the formations — is very 

 curious, differentiation being a decided feature. 



We find then that this cone-in-cone is characterized by its 

 sandwiched, or cake-above-cake, shale — or sandstone — interbedded 

 structure, and possesses an obvious and yet an indefinite nucleus-like 

 centre, towards which the cones and parts of cones radiate. But the 

 nucleus of these Portage masses is not usually a nodule 1 ; it is only 



Section through a typical cone-in-cone-bearing nodule, Portage Series, 

 Pennsylvania. 



[The cone-in-cone portions are confined to broad circular bands, tapering 

 away at their edges, upon both the upper and lower surfaces.] 



a portion of what appears to be an ordinary layer of false-bedded 

 sandstone. Now, where the sandstone comes within the range or 

 confines of the conic masses it is decidedly calcareous. The cone- 

 in-cone invariably contains calcium carbonate, while the enveloping 

 layers of shale rarely show more than a trace of that salt. 



It is important also to notice that cone-in-cone, although 

 associated and sometimes intricately intercalated with the thin 

 arenaceous laminae, is nevertheless confined to the more argillaceous 

 — the shaly layers. Another feature is that an individual layer or 

 lenticular cake of the structure has not restricted itself in process of 

 formation to any one particular band of the shale, but, as shown in 

 PI. XXXV. fig. 5, incorporates portions of several different bands. 2 

 That there exists any difference in any particular between the conic 



1 When well-developed nodular masses carrying cone -in -cone do occur in 

 these beds, the upper and lower coatings of the cones, instead of being drawn 

 around the rims of the nodules (as Mr. Young appears to find them), are 

 squeezed and somewhat elevated into annular forms near the rims of the stone 

 on either side (see fig.). 



2 Does not this fact alone prove that Mr. Young's idea of the origin, etc. of 

 the formation cannot stand ? 



