Kemp — Geology of Essex County. 



595 



extent below ground. Others often stand in full exposure, 10x20 feet 

 in dimensions. The district is the most prolific in them of any traversed 

 by me. 



Along the highway in the northeast corner, gneissoid anorthosites. are met 

 at No. 103 and alternating with gabbros (No. 104) they continue along that 

 road over to the Valley of the Schroon. On the highway in the Schroon 

 valley, massive gabbro is met at No. 103a, and massive anorthosite at No. 105. 

 Gneissoid anorthosite forms the north shore of Paradox lake at No. 106a and 

 No. 106b, but quartz gneiss outcrops at No. 106. On the west side of the 

 road up the Schroon valley, the anorthosites are met in the hills and have 

 gneissoid laminations more or less distinctly developed. In the foothills to 

 the north of Rogers pond, thinly laminated basic gneisses, manifestly derived 

 from gabbros, are first traversed and only yield to the more massive forms in 

 the interior peaks. The region where Nos. 85, 86 and 86a appear is a very 

 difficult one to cross, as there are no trails and as it has been recently burned 

 over. On the northwest, gneissoid anorthosites again appear at No. 88, and 

 over to the north of Bailey's pond, with varying accessions of dark silicates, 

 they continue to the North Hudson line. 



The exposures and float masses of the rocks of Series III in this 

 town have given some of the most interesting data regarding the dynamic 

 lnetamorphisui of these rocks that have been met in the mountains. Perfectly 

 massive varieties were collected, consisting of a coarse aggregate of green 

 labradorite, with perhaps a stray hypersthene, augiteor hornblende crystal and 

 a garnet <>r two. Crushed rims around the crystals first manifest themselves 

 and increase gradually until the rock consists of nucleal fragments embedded 

 in a white pulp of comminuted feldspar. Such varieties I have called pulp 

 anorthosites. Apparently these have resulted largely from crushing strains 

 without much shearing. When the latter is superadded, the crushed materials 

 are dragged out into the laminations of a gneiss, with the nucleal crystals left 

 as lenticular "eyes "around which the laminae pass. Abundance of dark 

 silicates accentuate the laminations, and the development of garnets makes 

 them much more prominent. The formation of this latter mineral is a 

 question deserving much careful study and chemical analysis. It is a 

 remarkably common and characteristic mineral all through the mountains and 

 is present in all the older rocks, but especially in those of Series III. It 

 seems to result from the pyroxenic constituent and also to develop in purely 

 feldspathic rocks, and in these it may be in fairly regular dodecahedra three- 

 fourths of an inch in diameter. It is a deep rich red in the rocks of Series 



