r68 



NEW YORK STATE MUSEUM 



record his belief that most, if not all of the Adirondack pre-Cam- 

 brian can be included in series 2 and 3 provided the former be 

 expanded so as to include igneous rocks which were contemporary 

 with, or followed closely on the deposition of the claetice, and 

 which are older than the eruptives of series 3. While such ®ub^ 

 division wholly fails to account for the floor on which the clastic 

 rocks were deposited, this floor is not to be discovered at present; 

 there still remains the possibility that it may be represented by 

 gneisses such as those of Clinton county. 



Order of succession of the Adirondack eruptives 

 In a region where the general rock relations were not con- 

 fused by severe metamorphism, such evidence as that adduced in 

 this paper would suffice to establish the order of succession of the 

 eruptives as flrst anorthosite, followed by syenite, granite and 

 lastly gabbro. Much later came diabase and syenite porphyry 

 dikes, though these are still pre-Potsdam in age. There are other 

 eruptives besides the four most prominent ones just mentioned, 

 but onlv in subordinate amount. 



CHEMICAL ANALYSES AND DISCUSSION 



1 



Si02 44.77 



AI2O3 12.46 



Fe203 

 FeO . 

 MgO.. 

 CaO.. 

 NasO , 

 K2O . . 

 HoO .. 

 CO2... 

 TiOg . 

 P2O5. 

 CI.... 



F 



S 



MnO.. 

 BaO .. 



4.63 



12.99 



5.34 



10.2 



2.47 



.95 



.6 



.37 



5.26 



.28 



.26 



.17 



trace 



2 



47.42 



17.34 



4.91 



10-22 



5.21 



8-09 



3-48 



1-89 



1.13 



3.6 

 -06 

 .21 



.06 

 .04 



3 



51.62 



24.45 



1.65 



5.3 



1-21 



9.97 



3.49 



1.27 



.72 



.01 



.1 



4 



54.47 



26.45 



1-3 



10.8 

 4.37 

 .92 

 .53 



o 

 54-62 

 26.5 

 .75 

 -56 

 .74 

 9.88 

 4-5 

 1.23 

 -91 



Total 100.75 100.01 



Sp.gr.. 3.09 



99.79 100.19 

 2.798 2.72 



)9.7 

 2.7 



6 



54.38 



20.53 



2.78, 



5-5 ) 



1.99 



5.39 



5.2 



3.4 



.5 



.09 

 .15 

 .03 

 .03 



.01 

 .16 



100.03 

 2.7 



7 

 57 

 16.01 



10.3 



1.62 

 6.2 

 4.35 

 3.53 

 .15 



99.16 



