N^otes on the New J^ossil, Dalmonelix 7 



quires time. And time is required for fossilization as well. 

 Therefore, the assumption that these fossils were burrows in 

 the sides of modern hills, seems untenable. So rapid is the 

 work of erosion here that the region is cut out and gullied at 

 such a rate that verdure cannot get a footing. Much less time, 

 then, is allowed for burrowing and for the fossilization of the 

 same. 



Another thing: it often happens that there are hard concre- 

 tionary layers lying horizontally in the sand-rock; layers too 

 hard for our well-tempered tools — therefore certainly an irre- 

 sistible barrier to burrowing animals. Yet underlying this 

 layer, and abutting directly against it are the tops of many 

 fossil corkscrews. It certainly suggests that these rocks were 

 laid by sedimentation over them. 



This hard concretionary layer often protects the softer un- 

 derlying rocks from excessive weathering, and so these cork- 

 screws are in some cases weathered out entirely, and there 

 they stand like fine spiral columns supporting the shelving 

 rock above. 



As far as the authors observations go, this whole region is 

 sedimentary, and the fossils followed the sediment upward 

 through one hundred and fifty to two hundred feet, or more, of 

 deposit. Some of the above points may have more meaning to 

 those interested if they will examine plate I, which gives a 

 view of Eagle Crag from the west. 



The exposure here is somewhat over one hundred feet, and 

 it may help in judging of heights and distances to have atten- 

 tion called to the two workmen digging at the corkscrews, one 

 above, the other below. The more abrupt portions of the 

 crag are thirty-five to forty feet high, and inspection will show, 

 even in the greatly reduced picture, many corkscrews on vari- 

 ous levels. However, granting that this fossil is nothing more 

 than the burrow of an animal, it loses none of its interesW<for 

 in that case we have preserved a most remarkable burrow, as 

 well as the skeleton of the animal which dug it. And, what 



