464 PROCEEDINGS OF THE ALBANY MEETING 



The next paper was presented without discussion : 



APPARENT UNCONFORMITIES DVRING PERIODS OF CONTINUOUS 



SEDIMENT A TION 



BY G. B. SHATTUCK 



The last paper of the day was the following : 



ORIGIN AND AGE OF AN ADIRONDACK AUGITE SYENITE* 

 BY H. P. CUSHING 



[Absii'tict^ 



Recent field work luis shown that there is a great body of eru})tive rocks in the 

 heart of the Adirondacks comprising gabbros, anorthosites, syenites, and granites 

 which grade into one another and represent outflows from a common source, not 

 widely separated in time. The order of eru})tion was anortliosite, syenite, granite, 

 and gabbro. Analyses were presented showing many intermediate types. These 

 intrusives are younger than the sedimentary gneisses of the region and than some 

 of the igneous gneisses also. All show some differentiation in situ, though of not 

 great amount. The syenite proves to be a most important rock in the region, oc- 

 cupying an area equally as great, if not greater, than does tlie anorthosite. It 

 ranges toward the anorthosite on the one hand and toward the granite on the 

 other, all intermediate varieties being found. Much of it was porphyritic and now 

 occurs as an augen gneiss, whose eruptive nature and original structure are per- 

 fectly apparent. There is also in the region much thoroughly gneissoid rock, of 

 the same general appearance and composition, which is often closely involved with 

 other sorts of gneiss. This maybe in part older, though no evidence is yet at 

 hand which would seem to indicate that this is so. In the absence of such, the 

 author's present disposition is to group all together, accounting for the differences 

 as due to variation in the severity of metamorphism from })lace to place. 



The paper was discussed by J. F. Kemp, A. P. Coleman, and the author, 

 and will be printed as a bulletin of the New York State Museum. 



The Society then adjourned. No evening session was held, but the 

 Fellows of the Society, with a few guests, had the annual dinner at 

 Keeler's hotel. The address of welcome, deferred from the opening ses- 

 sion, was made by Doctor T. Guilford Smith. 



Session of Friday, December 28 



The Society met at 9.30 a m, President Dawson in the chair. 

 The report of the Council was taken from the table and adopted with- 

 out debate. 



* This paper is presented by permission of the state geologist. 



