TITLES AND ABSTRACTS OF PAPERS 99 



TITLP:S AND ABSTRACTS OP PAPERS READ BEFORE THE SATURDAY MORNING 



SESSION 



FIELD RELATIONS OF LITCHFIELDITE AND SODA-SYENITE OF LITCHFIELD, 



MAINE 



BY REGINALD A. DALY 



(Ahstract) 



The original type of nephelite syenite, litchfieldite, hitherto known only in 

 the form of glacial erratics, has been fliscovered in a place near South Litch- 

 field, Maine. The rock occurs as small lenticular injections, roughly parallel 

 to the vertical schistosity and bedding of the inclosing sediments. Nephelite- 

 free, soda-rich syenites constitute associated injections of similar form and 

 relations. 



Eead by title in the absence of the anther. 



ADIRONDACK ANORTHOSITE 

 BY WILLIAM J. MILLER 



{Ahstract) 



This paper dealt with the whole problem of the structure and origin of 

 anorthosite, with special reference to the Adirondack region. Particular atten- 

 tion was* given to Bowen's recent paper in the Journal of Geology, in which 

 he elaborates an hypothesis to account for the structure and origin of the 

 Adirondack anorthosite. As a result of six months of detailed field-work within 

 and close to the great anorthosite area of northern New York, the present 

 writer finds Bowen's hypothesis untenable. 



Further evidence in support of Professor Gushing" s contention that the anor- 

 thosite is a separate intrusive body distinctly older than the syenite-granite 

 series was presented, but many new points which have important bearings on 

 the whole problem were considered. 



Among the principal topics discussed were the following : Variability of the 

 anorthosite and its significance; the chilled border fades and its significance; 

 relation of the anorthosite to the Grenville series; relation of the syenite- 

 granite series to the anorthosite; anorthosite and syenite-granite iriixed rocks; 

 general absence of syenite and granite from the anorthosite area, and probable 

 origin of the anorthosite by clifferentiation on a laccolith of gabbroid magma. 



Read in abstract from manuscript. 



DlSCUSSION 



Dr. W. S. Bayley congratulated Professor Miller on his attempt to study 

 the anorthosites in the field rather than in the laboratory. He corroborsited 

 the speaker's observation that the anorthosites are not pure feldsi)ar rocks. 

 In Minnesota the anorthosite passes by uniform gradations into olivine gabbro, 

 all phases of the gradations being recognizable. 



In the highlands of New Jersey — an area in which the geology is very 

 similar to that of the Adirondacks — the quantity of syenite gneiss is so great 



