the Hudson and its Tributaries. 



307 



an apparent reversal of drainage — that is they come in from 

 the southwest and turn a sharp corner so as to flow to the sea 

 in a southerly direction. The lower Esopus, the Rondout, the 

 Wallkill and the Moodna all conform to this rule, as will be 

 seen from fig. 1, while on the east bank the streams enter from 

 the northeast. The relations are due to the geological struc- 

 ture. The strike of the rocks and the trend of the ridges are 

 northeast and southwest. The Shawangunk ridge, the wonder- 

 fully folded and faulted Helderberg strata and the Archean 

 Highlands are particularly influential. The upper waters of 

 Esopus Creek come across the flat opposing dip of the Hamil- 

 ton until they strike the folded lower strata and then make 

 the turn. In the upper waters the joints are the chief struc- 

 tural influences, the stream on the whole adopting a resultant 

 between the 1ST. 21 E. and the N. 71 W., although sometimes 

 on one set, sometimes on the other. 



Tributaries on the West Bank. 



The Tongore Crossing of the Esopus. — This is shown in 

 fig. 2, which is drawn looking down stream or southeast. 

 The stream at this point flows nearly east, along the minor 

 series of joints N. 71 W. It has cut a steep gorge in the 

 flagstones and shales to the 320 ft. contour. On the south 

 bank the bed-rock rises above the 550 ft. contour and is often 



Fig. 2. 



NE 2 



__j5vy___^ 



• , ,o/-Vo. , ;. < ! ■'■.o.'. : .o.; .v77rr-^ry-___ s^.- '.•©-.:•.: -©*x So ^-^^^ ~ ~. — — — " 



•;.■<)•. :.oio/ ; »v-v^%.'»: , ^:-bVA p . : i? T ^'S<. :r «»'':La^ l {J} ^ soo' — — _. 



— i a> 



— — 







" =L - — — ~ — ~=- ~±— ~^~S Ea" l eve l~-^=T- _zr : 



Fig. 2. The Esopus channel. The bed-rock is the Hamilton 

 and shales. 



exposed, but on the north bank drift conceals all the rock. A 

 series of borings has shown the cover to vary from 60 to 250 

 ft., and that a buried channel exists at 240 ft. A.T., or about 

 70 ft. below the present river. Its sides have gentle slopes and 

 its profile is that of a much more mature stream than the pres- 

 ent Esopus, from which it is distant about 2,000 ft. to the north- 

 east. Several other crossings have also been explored, but this 

 one will serve to illustrate the relations in altitude. 



The Hurley Crossing of the Esopus. — In its southeasterly 

 course the Esopus breaks through the Hamilton escarpment 

 and strikes a broad open valley, with all the characteristics of 

 an old lake bottom, located upon some well-developed valley 



