C. H. HITCHCOCK — OVAL GRANITOID AREAS. 557 



After recess, the first paper read was — 



SANDSTONE DIKES. 

 BY J. S. DILLER. 



The paper was discussed hy W. M. Davis and B. K. Emerson, and is pub- 

 lished among the memoirs, forming pages 411-442, with plates 6-8, of this 

 volume. 



This paper was followed hy — 



ILLUSTRATIONS OF GLACIERS IN SELKIRK MOUNTAINS AND ALASKA. 



BY A. S. BICKMORE. 



A series of elahorate lantern slides were thrown upon the screen and 

 hriefly described. 



The next paper was — 



SOME RESULTS OF ARCHEAN STUDIES. 



BY ALEXANDER WINCH ELL. 



It gave rise to discussion by C. R. Van Hise and Professor Winchell. 

 The paper is published among the memoirs, ante, pages 357—39 I. 



The paper represented by the following abstract was then read : 



SIGNIFICANCE OF OVAL GRANITOID AREAS IN THE LOWER LAURENTIAN. 



BY C. II. HITCHCOCK. 



[Abstract.] 



In the primitive crystalline regions, observers have noted that the supposed oldest 

 portions of the Laurentian consist of oval, ovoidal, elliptic, or variously elongated 

 ureas, usually foliated. Such are the formations called K,, K.,, K 8 by Percival in the 

 "Western Primary" of his Connecticut map, as well as his 15 of the " Eastern Pri- 

 mary." The first-named are part of a series that extend through western Massa- 

 chusetts into Vermont, and would be represented in the " Laurentian protazis of the 

 Green mountains " as described by Professor J. I). Dana in the Bulletin (J. S. A., 

 this volume, page 36. In New Hampshire tiny may be represented by the porphy- 

 ritic gneiss and the Bethlehem gneiss. Dr. A. C. Lawson describes similar areas in 



LXXIV— Bull. Geol. Soc. Am., Vol. t, 1889. 



