1905.] NATURAL SCIENCES OF PHILADELPHIA. 871 



these fragments, before they disintegrated entirely, were caught in the 

 flow of siHca and carried gently outward and deposited where they are 

 found at present, surrounded by the almost snow-white silica. As the 

 sandstone is itself often very white, the outline of these fragments is 

 not readily distinguished in the sides of the open cuts, until they have 

 been exposed for some time to the weather. However, it is to be remem- 

 bered that there are in the silica, as far as we have explored it with 

 trenches and shafts, great numbers of perfectly solid coherent sharply 

 angular pieces of sandstone and limestone, as well as of the incoherent 

 fragments. So far as it can be observed the white sandstone stratum, 

 where it is exposed beneath the limestone cliffs inside the crater, is in 

 this same incoherent condition. It is as if it had received a tremendous 

 blow, the concussion from which caused the solid sandstone to disin- 

 tegrate and become almost like compacted sand, since it can in many 

 instances be dug out and crumbled by the fingers. The effect of this 

 has been of course to cause the sandstone stratum at this point to 

 occupy more space than it previously occupied. The result of this has 

 undoubtedly been the raising of the superimposed limestone and red 

 sandstone strata, causing them to show, when viewed from the interior 

 of the crater, several anticlinal and synclinal folds, and to dip out- 

 wardly from the center of the crater, and in this way assisting in 

 forming the elevation locally known as Coon Mountain, which has 

 already been described. 



No order is to be observed in the distribution of the angular frag- 

 ments either within or without the crater, excepting that which I have 

 already referred to, that the greatest amount of large limestone frag- 

 ments, which it should be remembered is the most coherent rock of the 

 series and the one which has most successfully resisted disintegration, 

 is to be found almost due east and due west of the center of the crater; 

 and also excepting that at certain places there are to be seen spurts of 

 one kind of solid fragments, for example white sandstone, aggregating 

 in amount thousands of tons, and extending from the rim of the crater 

 almost down to its base. 



These tongues of fragmentary material, which seem to have been 

 spurted out of the crater with such force as to displace everything which 

 they met, are very interesting ; especially those of the white sandstone, 

 some of the fragments of which exhibit very beautiful examples of 

 cross-bedding. The lowest members of the series which was ejected 

 are the red sandstone and the overlying yellow sandstone, small pieces of 

 which are to be found in relatively small quantities on the surface of 

 the southern and southeastern portion of the rim. These are almost 



