14 NEW YORK STATE MUSEUM 



To indicate the areal occurrence of the mineral resources, the 

 most convenient method will be to divide the State into provinces 

 in accordance with their geological makeup and history. Thus the 

 Adirondacks with their ancient igneous and metamorphic rocks 

 constitute one province, the Highlands with similar formations 

 another, the Taconic area of metamorphosed Paleozoic strata a third, 

 and the interior region of unchanged Silurian and Devonian sedi- 

 ments a fourth. The Palisades with the Newark sandstone and 

 volcanic rocks and the coastal plain of Long Island and Staten 

 Island constitute separate but minor provinces. 



Adirondack province. The Adirondack Precambrian province 

 comprises an area of about 12,000 square miles. It is roughly- 

 circular in outline with an average diameter of 125 miles. The 

 surface is broken and rugged everywhere, but not uniformly moun- 

 tainous, although much of it is covered by ridges and peaks that 

 reach elevations of from 1000 to a little over 5000 feet. The ridges 

 usually trend northeast and southwest, parallel with the main 

 folding and fracture lines. Along the borders the Precambrian 

 crystalline rocks are succeeded by Paleozoic strata in horizontal 

 beds, with a profound unconformity to mark the interval between 

 the two series. 



The oldest formations are a group of highly metamorphosed 

 sediments, the Grenville strata, which are upturned, often intricately 

 folded and much broken up by invasions of plutonic igneous rocks. 

 The Grenville strata occur in belts and irregular patches that are 

 remnants doubtless of once continuous beds that spread over the 

 whole Adirondacks. Their thickness is not determinable with 

 accuracy although altogether they probably represent a succession 

 of several thousands of feet. Despite their great age the strata do 

 not differ materially from the more recent water-laid detrital 

 deposits — sandstones, silts or shales and limestones — after allow- 

 ance for the high degree of metamorphism they evidence. 



The igneous intrusions that invade and break up the Grenville 

 include enormous bathyliths, like that of the anorthosite in the 

 eastern Adirondacks which is 50 miles across and the syenite bathy- 

 liths in the northern Adirondacks, and also as stocks, bosses and 

 dikes. The granites in their molten state seem to have been par- 

 ticularly mobile and fluid, so that their great masses are represented 

 mostly by innumerable dikes, stringers and bosses that have pene- 

 trated the Grenville nearly ever3rwhere and effected changes of 

 composition and physical features. The granites also are the most 

 influential of the igneous rocks in contact effects and in places have 



