ORIGIN OF CAVES OF PUT-IN-BAY ISLAND 563 



Following the discussion of Professor Kemp's paper the Society 

 adjourned for the noon recess. 



At 2.20 o'clock p m the Society reconvened, and the first paper read 

 was 



ROCK CLEAVAGE 

 BY C. K. LEITII 



This paper is published as Bulletin number 239 of the U. S. Geological 

 Survey. 



The second paper was 



ORIGIN OF THE CA VES OF THE ISLAND OF PUT-IN-BA Y. LAKE ERIE 

 BY EDWARD H. KRAUS 



[Abstract] 



The rocks of the Lower Helderberg are locally very much disturbed. The 

 largest of the four caves open to the public is Perry's. The ceiling of this cave 

 shows the folding very clearly and also some interesting irregularities, in that all 

 the strata do not extend entirely across the cave. This gives the ceiling an appear- 

 ance similar, to some extent, to an inverted steps. The floor of the cave conforms 

 to the unevenness of the ceiling, for where there is a depression in the former there 

 is a corresponding projection downward in the latter and vice versa. This phe- 

 nomenon is, no doubt, the result of folding and subsequent collapse. In all prob- 

 ability the folding was caused by the hydration of anhydrite, for large deposits of 

 gypsum have been encountered in the sinking of wells in the immediate vicinity. 

 Cores from these wells show a large amount of brecciation. Inasmuch as the 

 increase in volume caused by the hydration of anhydrite may be as high as 60 per 

 cent, and since there is a large supply of water present to bring about the solution 

 of the gypsum thus formed— the level of the lake is reached at a depth of about 40 

 feet— we have given the probable causes for the folding, leaching, and subsequent 

 collapse. 



Remarks were made by A. C. Lane, G. K. Gilbert, E. H. Kraus, M. L. 

 Fuller, H. P. Cushing, and the President. The paper is published in the 

 American Geologist, volume xxxv, pages 167-171, March, 1905. 



The third paper was 



MOUNTAIN GROWTH AND MOUNTAIN STRUCTURE 

 BY BAILEY WILLI8 



Remarks were made by A. C. Coleman, with reply by the author. 



Announcement of details relating to the annual dinner and the even- 

 ing session were made by the Secretary. 



