ORIGIN OF THE HUDSON RIVER GORGE 499 



bordering the river between West Point and Fort Montgomery. The inference 

 from stratigi-aphic continuity is therefore that the Hudson river from West Point 

 to Fort Montgomery follows a synclinal valley, along the bottom of which is a 

 narrow belt of limestone bordered on either side by schistose rocks which have been 

 more susceptible to erosion than tlie massive granites of the Highland mountains 

 which form the walls of the valley. This feature, which is characteristic of the 

 central portion of the gorge, does not exist at its northern and southern extrem- 

 ities. Each of these is much shorter than the central part and has a trend quite 

 oblique to it. 



An examination of the terminal portions shows that their determining cause is 

 not a syncline of softer gneisses and limestone, but a synclinal cross-folding of the 

 granite, which is characteristic of the crystalline area of southeastern New York 

 and has everywhere an important influence on its drainage. This cross-folding is 

 usually attended by fracture, and although we cannot positively assert tliat the 

 latter has occurred at the two points mentioned, it is highly probable that the 

 work of erosion has been aided in this way. 



10 WAN DRIFT 

 BY SAMUEL CALVIN 



The paper is printed as pa2;es 107-120 of this volume. 



LOESS DEPOSITS OF MONTANA 

 BY N. S. SHALER 



The paper is printed as pages 245-252 of this volume. 



SPACING OF RIVERS WITH REFERENCE TO HYPOTHESIS OF BASELEVELINQ 



BY N. S. SHALER 



The paper is printed as pages 263-276 of this volume. 



The general session was then transferred to the room where the Petro- 

 graphic Section was yet in progress. The work in this special section 

 was as follows : 



Proceedings of the Petrographic Section 



This temporary section was convened on Friday, at 2 o'clock p m, 

 in the geological lecture-room of Schermerhorn Hall. Vice-President 

 Emerson was made chairman and J. F. Kemp secretary. Six papers 

 were read before the section, the first of which was 



DIFFERENCE IN BATHOLITHIC GRANITES ACCORDING TO DEPTH OF EROSION 



BY B. K. EMERSON 



[Abstractl 



It was stated that the Quincy granite band with the associated quartz-porphyries 

 rhyolitic breccias, and granophyrs extended south beneath the Carboniferous to 



