SCIENCE. 



[N. S. Vol. XII. No. 290. 



the same derivation can be established for 

 others . While deeply buried, the sediments 

 have been invaded by an enormous mass of 

 plutonic eruptives, of whose nature and suc- 

 cession we now have much evidence. So 

 extensively has this been true on the East, 

 that the sediments are broken up into small 

 and often isolated areas, whose relations are 

 difiBcult to decipher. On the west as shown 

 by C. H. Smyth, Jr., they are more exten- 

 sive although everywhere pierced by erup- 

 tives. After the intrusions dynamic meta- 

 morphism of a pronounced type crushed, 

 sheared and mixed them up with the igneous 

 intrusions; upheaval and faulting disguised 

 the relations ; and erosion removed or ob- 

 scured the evidence, so that a problem is 

 afforded, that is much the same as if the 

 Basement Complex of the Marquette region 

 had invaded the Huronian sediments and 

 had split them up into small areas after 

 which faulting had ensued. And yet in 

 the eastern Adirondacks it does not appear 

 that close folding has very largely if at all 

 taken place. On the contrary, despite the 

 dynamic metamorphism, the decipherable 

 dips in the ancient sediments and the con- 

 tacts between limestones and neighboring 

 gneisses are often flat, and low folds if any 

 seem to be the rule. N"evertheless crush- 

 ing and granulation are very wide- spread 

 and have often produced mashing in the 

 rocks of all sorts, except the latest trap 

 dikes. The mashing cannot be due to the 

 larger intrusions, because they exhibit it as 

 much as the sediments, and it must have 

 followed their entrance. It preceded the 

 Potsdam and it must have taken place un- 

 der a considerable load, else there would 

 have been more severe folding. From this 

 brief general statement it will be seen that 

 the problems possess their own individual 

 characters and in a measure seem to differ 

 from those of other regions unless it be 

 Quebec and Ontario. 



Recent Geological Work. — I pass over all 



mention of earlier workers in the region, 

 because their contributions have already 

 been reviewed elsewhere by me, and be- 

 cause they were not serious in a strati- 

 graphical way. Detailed fieldwork has 

 been required and this has only been at- 

 tempted by C. H. Smyth, Jr., H. P. Gush- 

 ing, myself and our assistants. Smyth has 

 worked in the western counties ; St. Law- 

 rence, Jefferson, Herkimer and western 

 Hamilton. Gushing has studied Clinton 

 and Franklin Counties on the north ; and I 

 have been busied with Essex, Warren, 

 Washington, eastern Hamilton, Saratoga 

 and Fulton. We have however kept in 

 close sympathetic touch in all our work. 

 In Gushing' s area less of the undoubted 

 sediments occur, as only two small expo- 

 sures of limestone have thus far been dis- 

 covered. In Smyth's area the limestones 

 are most extensive and furnish the best 

 large exhibitions, whereas in the region 

 covered by myself, they are most numerous, 

 although of smaller individual extent, but 

 they have associated with them certain 

 other forms of metamorphosed sediments, 

 which are not yet recorded iu such large 

 amounts elsewhere, which are of special 

 interest ; and which throw light on the 

 nature of the series. Smyth has suggested 

 the name Oswegatchie series for the lime- 

 stones and their associates on the West, 

 and while the equivalency of the rocks 

 with the previously named Grenville series 

 of Canada seems probable in a general way, 

 we all have agreed to use this term. Any 

 term must however be considered more or 

 less provisional because as will later appear 

 there is a great gap in outcrops between the 

 original exposures of the Oswegatchie, along 

 the river of the same name, and the near 

 neighbors to it, on the one hand, and the next 

 exposures to the southeast on the other. 



VARIETIES OP SEDIMENTARY ROCKS. 



Before discussing the general distribution 



