22 NEW YORK STATE MUSEUM 



coarse-grained and only slightly foliated, looking like an altered de- 

 rivative of the gneisses. The fault that borders Bald hill on the 

 east may be within the Bald hill gneiss for a distance. 



North along the road toward Fishkill Village the rock beco.nes 

 more foliated. A thin section of this variety shews some biotite in 

 addition to hornblende, but the former is decidedly subordinate 

 and is apparently secondary. 



Two mountain roads over this spur from the Cold Spring road 

 to West Fishkill Hook give fair sections. There are also numer- 

 ous outcrops in the fields to the north and south. Surface exposures 

 are confusing both as to structure and petrographic characters. In 

 some places the gneiss apparently dips to the northwest at low angles, 

 but where the foliation planes may be detected, they dip to the 

 southeast at high angles. The rock often has a granular and hybrid 

 character that seems best interpreted as the condition resulting 

 from the induration of a partially disintegrated rock which is pri- 

 marily a very ancient character. The apparent northwest dip is 

 accordingly best explained as a sort of exfoliation between the basal 

 gneiss and the altered surface derivative. 



On the whole, the section is across a series of " strata " showing 

 tendency to definite alignment with each other and to variety of 

 composition. In the main the recks of this spur may be classified 

 as micaceous and hornblcndic gneisses forming rather thick 

 " strata," which usually exhibit uniformity in mineralogy for some 

 distance across the strike. 



The road from Brinckcrhofi:' to Johnsville crosses this spur north 

 of Mount Honness proper. Fine exposures have been made in the 

 dark colored hornblende gneisses along the road in the process of 

 constructing the new State road, and in the quarries just south of 

 Arvis Haight's, from which stone was removed. These sections 

 show thick masses of the hornblende gneiss. Lighter colored 

 gneisses have been noted interstratified with the hornblende 

 varieties. 



In connection with the question of the origin of the hybrid char- 

 acter of the gneiss along the northwestern slope of this spur it is 

 interesting to note that the slope is gentle. Although it now lies 

 in a faulted position against the limestone, the basal quartzite may 

 have reposed on the gneiss along this slope subsequent to the eleva-. 

 tion which brought the gneiss against the limestone. 



More distinct " passage beds " overlying the inclined gneiss occur 

 just beyond the point where the two mountain roads cross on the 

 crest of the ridge. Between the eastern fork of the roads thus 



