12 



pounds to a hundred pounds or more in weight, each showing 

 more or less perfect rings. One of these was like a dumb-bell 

 made of two of the circles, each three or four inches in diameter 

 with six or eight rings strongly welded together, which appeared 

 to have weathered out under glacial erosion or later disintegra- 

 tion of a larger boulder. This I sent to Dr. Berkey. He too was 

 much interested, and also referred them to. his associates, Dr. 

 G. Marshall Kay and Mr. G. I. Atwater, who made thin sec- 

 tions. Dr. Kay reported that his conviction was that the speci- 

 mens were of inorganic character. He wrote: "This is evident 

 from the fact that the bedding in the rock passes directly 

 through the spherical masses. The concentric spheres in the 

 weathered specimens are due to the presence of layers about the 

 center of the mass that are differently cemented, with the re- 

 sult that the more poorly cemented spherical layers have been 

 more disintegrated than their adjacent better cemented layers. 

 From a petrographic study of the sections, it seems that an 

 original sandstone has been silica cemented, the cement being 

 added as enlargement of grains. This cement has in turn been 

 replaced in concentric zones about a central point by iron oxide, 

 this replacement in some instances having also affected the 

 original grains of sand. These iron-oxide cemented zones have 

 disintegrated more readily than those in which the silica cement 

 has not been replaced. The structures are most similar to con- 

 cretions, though they differ from such structures in that the 

 concentric banding is due to zonal replacement of the cement 

 in a quartzite rather than to a zonal cementation of sandstone. 

 In summary, the structures in the specimens of the Shawangunk 

 quartzite are concretion-like structures that bear no evidence 

 of organic origin." 



Mr. Atwater's report was that the specimen showed bedded 

 sedimentary original structure, with cementation by silicifica- 

 tion, and replacement; that the grains were of quartz, probably 

 originally from vein quartz; quartzite, and infrequent argillite, 

 titanite and tourmaline, with chlorite as an alteration product 

 formed partly after cementation and possibly partly introduced 

 as inclusions in the quartz grains. 



Dr. Berkey, expressing the same views as those of his asso- 

 ciates, remarked: 



"The specimens make a striking exhibit and are, to say the 



