68 Ailing — Problems of Adirondack Precambrian. 



old sediments. One thousand feet of the series have 

 been studied in detail and subdivided into 12 formations 

 "which can be traced over considerable area. 



3. That individual phases of the Saranac Series may 

 be some one or other of the well recognized rock units, 

 yet it is quite possible that other phases cannot be so 

 classified. 



4. Recognition of the presence of an ancient meta- 

 gabbro antedating the Laurentian granite. 



5. Recognition of the presence of a granite (quartz 

 monzonite) older than the anorthosite-syenite-granite- 

 gabbro series. This is the Laurentian granite. 



6. The establishment of a metagabbro closely follow- 

 ing the intrusion of the Laurentian granite. 



7. Some amphibolites were found to be of sedi- 

 mentary origin, that is, members of the Grenville series, 

 while others are metagabbros. Criteria for the recog- 

 nition of the different types are here presented. 



8. The occurrence of the Algoman gabbro and the 

 normal diabase in laccolithic bodies. 



9. The presence of some peculiar gabbroic dikes. 



10. The post-diabase age of the camptonite and bos- 

 tonite dikes. 



11. That the faults of the Adirondacks are not all of 

 the same age. 



400 Oxford St., 

 Rochester, 1ST. T. 



