GEOLOGY OF THE NEW YORK CITY AQUEDUCT 85 



Five lines of wash borings were followed, and the results of these 

 are indicated in the accompanying figures. A -miaximum^ depth of 

 263.5 f^^t is shown by these wash borings. 



d Danskammer line. This line is about a mile south of New 

 Hamburg. Two lines of wash borings were made, reaching a 

 maximum depth of 268.5 f^^t. In this case slates standing almost 

 vertical form the east bank and limestone dipping gently eastward 

 the west bank of the river. Whether there is a deeper gorge or a 

 more complex structure here is wholly unknown. 



Of the three remaining lines, all of which are within the High- 

 lands, that one projected between Storm King mountain on the 

 west and Breakneck ridge on the east has been much the most 

 thoroughly explored. It is known as the Storm King line. The 

 other two have seemed to merit less attention. One crosses the 

 river from Crows Nest mountain to Little Stony point and Bull 

 mountain just north of Cold Spring, and is known as the Little 

 Stony point line. The other crosses at Arden point about a mile 

 south of West Point and Garrison. 



e Arden point line. Only wash borings were made. A 

 maximum depth indicated by this method is 220 feet. Structurally 

 this location appeared to have disadvantages, and although the 

 evidence as to bed rock conditions is confined to the natural out- 

 crops, there is no doubt but that it has objectionable features of this 

 sort. 



The Hudson follows closely the structural control in this portion 

 of its course. These structural elements include the foliation, the 

 bedding of the original sediments, the subsequent shearing zones, 

 and the strike of folds and faults. Crushed and sheared zones are 

 nowhere in the Highlands seen so extensively developed as on the 

 islands and the east bank of the Hudson in this, the central portion 

 of its Highlands course. The river is very narrow, being only 2120 

 feet on this line. 



■f Little Stony point line. The river here is 2360 feet wide. 

 The rocks on each side are similar and give no clue to possible 

 depths of channel. Less than 200 feet was reached by the lines of 

 wash borings. Three drill borings penetrated the stony or bouldery 

 river filling somewhat deeper — one near the center reaching 322 

 feet. None, however, reached bed rock. 



g Storm King crossing. Extensive exploratory work has 

 been carried on at this point, both on the banks and in the river. 

 Wash borings as usual have given poor results. Two diamond drill 

 holes were run at an angle toward and beneath the margins of the 



