ROBERT HAY SANDSTONE DIKES. 



55 



These dikes may be related to the phenomena of mud volcanoes, as they were 

 certainly intruded from below ; and they may be expressive of the closing period 



Figure 22 — General View of Dike number 2. 



of the Black hills uplift. Wedo not desire here to enter into this question, but sim- 

 ply contribute the facts for future study of what may fairly be called a new subject* 



Mr. Hay's paper was discussed by C. R. Van Hise and J. E. Wolff. 



Mr. Gilbert resumed the chair, and after announcements declared the 

 Society adjourned to the evening session. 



Evening Session op Monday, August 24. 



The Society reconvened at 8 o'clock p. m., the acting President, Mr. 

 G. K. Gilbert, in the chair. 



Some announcements were made, after which the following paper 

 was presented : 



SOME RECENT EXPERIMENTAL REPRODUCTIONS OF SCOTTISH MOUNTAIN 



STRUCTURE. 



BY HENRY M. CADELL, ESQ., OF BO'NESS, Scotland. 



This paper was illustrated with colored charts, and was followed by a 



paper of similar character, illustrated with lantern views, entitled : 



MECHANICS OF APPALACHIAN STRUCTURE. 



BY B \ii.ky w 1 1. 1. is. 



The papers of Messrs. Cadell and Willis were discussed together by 

 .1. E. Wolff, Joseph he Conte, C. D. Walcott, and the authors. 



♦ After the meeting the writer was informed by Dr. Hoist thai there are Bimilar dikes in Sweden, 



and Professor Hill states that something of the s ■ kind exists in Texas, and there appear i" be 



some in tin- "bad lands" of South Dakota. 



