ABSTRACTS OF PAPERS 63 



nate through metamorphism by heat and perhaps pressure of the tufaceous 

 forms. The evidences of this are briefly summarized as follows : 



I. By heat : 



(1) The presence, in the forms mentioned, of the interstitial f eld- 

 spathic glass, maskelynite, and calcium phosphate, merrillite. 



(2) The absence of glass, other than maskelynite, in the chondrules. 



(3) The presence in the interstices of fine granular polarizing parti- 

 cles and the "netzbroncif structures of Berwerth. 



II. By pressure : 



(1) The granulation of the radiate enstatite chondrules and their 

 gradual merging into the crystalline ground. 



(2) The distortion, and at times almost obliteration or destruction, 

 of a chondrite of whatever type. 



The paper is regarded as but a preliminary announcement of results 

 to be given in detail later. 



Presented by title at the request of the author. 



PORPHYRITIC GRANITIC GNEh'^SES, INTERPRETED AS LIT-PAR-LIT 

 INJECTIONS OF SCHISTS 



BY JAMES F. KEMP 



{Abstract) 



Observation of a so-called porphyritic, gneissoid granite in the Salmon River 

 Canyon of Idaho the past summer convinced the writer that it was an injected 

 biotite schist. The case was described, with comments on others of similar 

 nature in the East. 



Presented without manuscript. 



ORIGIN OF ADIRONDACK MAGNETITE DEPOSITS^ 

 BY WILLIAM J. MILLER 



(Ahstract) 



In 1919 the writer published a paper on the "Magnetic iron ores of Clinton 

 County, New York" (Economic Geology, volume 14, pages 509-535), special 

 attention being given to the elaboration of a new theory of the origin of the 

 ore deposits, particularly the large deposits now being mined at Lyon Moun- 

 tain. Certain criticisms of that theory have been published by Newland (Eco- 

 nbmic Geology, volume 15, 1920, pages 177-180). It is the purpose of the 

 present paper to reinforce that theory by additional evidence from field and 

 laboratory, to apply, the theory to Adirondack non-titaniferous magnetite de- 

 posits in general, and to answer Newland's criticisms. 



The problem of the origin of magnetic iron ore deposits has been a puzzling 



* Published by permission of tbe State Geologist of New York. 



