4:64: 



Report of the State Geologist. 



southeastward into the heart of the region. Nevertheless, no fixed limit has 

 been found in this section beyond which the limestone can l>e said not to 

 extend. It does not disappear, but simply decreases, occurring in smallei and 

 more scattered areas. If it were regarded as a distinct formation (a point to 

 be considered later), it could not be mapped as constituting a clearly defined 

 and continuous area, but would necessarily be represented in detached 

 portions; and facts now at hand indicate that such portions occur scattered 

 all through the Adirondacks. Hence the distribution of the limestone forma- 

 tion is, in a sense, co-extensive with that of the entire series of crystalline rocks 

 comprised in the Adirondack region; and the task of mapping the limestone 

 formation, be it called Huronian, as has been suggested, or, as preferred by the 

 writer, by the local term Oswegatchie, involves the entire problem of the 

 Adirondack geology. For to map the limestone formation, its geologic 

 limits must be first ascertained, and this necessitates the determination of 

 its relations to the associated rocks. In the case of the anorthosites and 

 gabbros, this has been done, as well as for some minor developments 

 of granite, etc. But the origin of the gneisses which cover the greater 

 part of the western Adirondack region, and their relation to the lime- 

 stone are, as yet, unsettled, and constitute a problem requiring careful study 

 for its solution. If, from such study, it should appear that the lime- 

 stones and gneisses together constitute a single series, it would make up 

 the whole of the area comprised within this report, except where 

 certain intrusive rocks occur, and would, indeed, with this latter exception, 

 probably make up the entire Adirondack region. On the other hand, should 

 the limestone and gneiss prove to belong to entirely distinct formations, it 

 would be a simple matter to trace their boundaries. But, finally, should it be 

 learned that some portions of the gneiss belong with the limestone in one 

 formation, while other portions belonged in another formation, then, judging 

 from experience in the field, it would become a very difficult matter to trace 

 the boundaries of the formations, on account of the perfect gradations 

 generally shown between different varieties of gneiss. The foregoing points 

 were, in part, touched upon in a previous report, but it seems worth while to 

 refer to them here, bearing, as they do, upon the whole question of aims, 

 methods and results of geologic investigation in the Adirondack region. < >ne 

 fact may be satcl\ j (remised, namely, that the different crystalline rocks of the 

 region are so related to one another that the study of one involves, to a greater 

 or less extent, the study of all, and the history of one portion can not be clearly 

 stated without reference toother portions. This is, of course, meant to apply 



