126 NEW YORK STATE MUSEUM 



It is of course quite impossible under the conditions governing the 

 present study to carry the correlation to great detail of identification 

 or to complete certainty. The nature of the formations themselves, 

 together w^ith their history, impose rigid limitations also upon such 

 a comparison ; but it seems possible to affirm with considerable assur- 

 ance that some of the individual members are represented in both 

 districts by essentially identical units. Such identical members, for 

 example, seem to be: 



1 The Grenville metamorphic sediments : 



Grenville of the Adirondacks-Grenville of the Highlands. 



2 The Injection granite as well as basic injections, meta gabbros, 



etc. representatives of the older igneous series. 

 Meta gabbros and granite gneisses of the Adirondacks-Pochuck 

 diorite gneiss and probably the Canada Hill granite of the 

 Highlands. 



3 The Syenite intrusive member of the younger series. 

 Syenite formation of the Adirondacks-Storm King granite and 



possibly Reservoir granite of the Highlands. 



4 The later basic dikes. 



Basic dikes of the Adirondacks-diorite dikes of the Highlands. 



Comparison with the Franklin Furnace district in northern New 

 Jersey. There is little doubt but that essentially the same series of 

 Precambrian rocks as is represented in the West Point quadrangle 

 extends indefinitely toward the south through northern New Jersey 

 and into Pennsylvania; but it is not at all certain that correlation 

 with the Adirondack types can be so fully determined for those 

 more distant areas. 



It thus happens that in the Franklin Furnace folio of New Jersey 

 a very different set of terms and divisions are used, and a less 

 definite outline of the historical sequence is indicated for them ; but 

 in a general way a certain similarity of history has l)een outlined for 

 that district also. The following quotation * covers this point : 



A comparison of the geology of the New Jersey Highlands with that of 

 the Adirondacks and eastern Ontario reveals the fact that the Byram, Losee 

 and Pochuck gneisses have their equivalents in the northern districts, and 

 that in general the three districts are essentially similar. 



The oldest rocks in the northern districts are crystalline limestones, quartz- 

 ites and micaceous schists that are considered to he metamorphosed sedi- 

 ments. Beneath these and also interlayered with ihem are augite gneisses 

 that may be mashed intrusive granites or the extreme phases of metamorphism 



■• Preliminary Account of the GeoloRy of the Highlands in New Jersey; 

 Baylcy, W. S,. Univ, of 111. Bui., v. 6, no. 17, p. 18, Feb. 8, 1909. 



