GENERAL STRUCTURE AND CORRELATION. 27 



lay the great Paleozoic ocean of America. 1 imagine, also, that the rocks 

 of this dry area had become disintegrated to a greater or less depth and 

 that the products of this action varied from kaolin and quartz at the surface 

 to semikaolinized material with fresh cores at depths. The depth of this 

 action would vary according to varying lithologic and topographic condi- 

 tions, as I have shown elsewhere. 1 



While the abrasion of the deeply disintegrated rock was progressing 

 along the advancing beach line the detritus of sand and pebbles arising 

 from this disintegrated material was deposited with varying proportions of 

 its constituents in a continuous sheet in progressive ''transgression" over 

 the previously dry land; 2 for I think the evidence offered by the erosion of 

 the Stamford dike is sufficient to show that the region owed its absence of 

 older sediments to its having been an area of dry land instead of an "abyssal" 

 area. 



During the progress of this removal and deposition of ready-prepared 

 material there would be places wher*e the underlying unaltered rock would 

 be washed clean and re-covered with sand and gravel. There would be 

 others where the material removed from the disintegrated mass would be 

 derived from the zone of semikaolinized fragmentary disintegration, and 

 places where this material would be deposited without having been much 

 rolled and in beds alternating with finer material. And again there would 

 be places where the disintegration was deeper — in basins as it were — and 

 where this material escaped removal and was covered by the sedimentary 

 beds. The recognition of these premises would, it seems to me, aid in the 

 explanation of many of the difficult points observed in the field. 



Take, for instance, the schistose lamination of the Stamford gneiss on 

 Clarksburg mountain, where this structure is most highly marked near the 

 contact with the overlying quartzite. The lamination is parallel in both rocks. 

 The quartzite here bends around the mountain and is highly crinkled, this 

 structure being defined by the micaceous constituent, and for some distance 



1 Secular rock disintegration, etc. Am. Jour. Sci., vol. 17. 1879, pp. 133-14-1. Also the applica- 

 tion and extension of the ideas advanced in that paper. F. von Richthofen: China, vol. 2, p. 758. 



■ F. von Richthofen has called attention to the fact that tor little importance has been attached 

 by geologists as a rule to the breaching and abrading action of the ocean when the beach line is 

 advancing landward. China, vol. 2, p. 768. 



