32 NEW YORK STATE MUSEUM 



Foliation 



All the Precambric rocks, except the diabase, show more or less 

 well-developed foliation. Details have already been given, and only- 

 certain broader features are here considered. 



In general, the most feldspathic rocks, such as anorthosite-gabbro 

 and certain basic phases of the syenite, are least gneissoid because 

 of a lack of minerals favorable for development of that structure, 

 while the granites, at the other extreme, rich in biotite and quartz, 

 are usually very gneissoid. Exceptions are, however, by no means 

 wanting, so that the degree of foliation among rocks of similar 

 composition may differ widely. 



The more representative dip and strike observations selected from 

 many notebook records are plotted upon the accompanying geologic 

 map. One of the most notable features is the remarkable uniformity 

 of strike over the whole quadrangle, with very few exceptions 

 ranging from east-west to northeast-southwest. Scarcely less uni- 

 form are the directions of dip which in the great majority of cases 

 is southward. The angles of dip range from low to high but with 

 dips of from 30 to 50 degrees distinctly prevalent. ]\Iany times 

 the amount of dip can not be determined. 



Other important features, rather common to the whole Adiron- 

 dack region, are the practical coincidence of stratification and folia- 

 tion surfaces in the Grenville ; the nearly perfect parallelism of 

 these to the foliation of the surrounding rocks; and the most in- 

 variable arrangement of Grenville masses with long axes parallel 

 to the foliation. 



PALEOZOIC ROCK OUTLIERS 

 The outlier at Wells 



At Wells is the largest and most interesting of all the Paleozoic 

 rock outliers in the Adirondack region. The nearest outcrops of the 

 general Paleozoic area are at Northville nearly 13 miles (air line) 

 from the most southerly exposures in the outlier. 



The first mention of this outlier was by Emmons in 1842 but 

 BO description was given. He said : '' At Hope I found a few 

 acres of Trenton rock, loaded with the usual fossils; and to the 

 south a few miles, the Calciferous, each in place." As Professor 

 Kemp has said,^ Emmons must have meant Wells instead of Hope, 

 since no such Trenton exposures occur at Hope. 



1 Geology of the Second District 1842, p. 417. 



