316 J. F. Kemjp — Buried Channels Beneath 



be interpreted by the drill-records, of which there are a satis- 

 factory number. Figure 11 illustrates the section interpreted 

 in the most reasonable way in order to account for the great 

 thickness of limestone, whose unrepeated thickness is known 

 to be about 1,000 feet. Utilizing folds only, it requires a com- 

 pressed sigmoid fold of limestone from whose anticline the 

 quartzite has been pinched out and from whose syncline the 

 slate. As against this a series of normal faults with southerly 

 dip might be imagined but are less likely since the prevailing 

 fault of this region is of the reversed type. 



The lowest channel is almost beneath the present stream and 

 stands at +10, somewhat unexpectedly high. 



The Croton River. — From the Peekskill crossing the aque- 

 duct bears away to the east and encounters so much high 

 ground as to reveal little of moment from the depressions. 

 But the earlier work in connection with the great dam across 

 the Croton River gives us abundant data regarding this stream. 

 Mica schist appears on the northwest bank and extends about 

 half way across the valley. It is then succeeded by white 

 marble to the south. The former would be interpreted by F. 

 J. H. Merrill* as metamorphosed Hudson River slate ; the 

 latter as the recrystallized Wappinger. A possibly different 

 view has been conservatively suggested by C. P. Berkey.f 



Summary of Tributaries, 

 west bank. 



Distance from Hudson 

 Name. in miles. Contour. 



Esopus 25-30 + 240 • 



Esopus (Hurley) 13-18 — 68 



Kripplebush .'. ._ 12-27 + 80 



Rondout 12 — 10 



Wallkill. Spr. A 12 - 79 



"13 13 



L'lle 17 + 65 



Moodna 2 - 59 



EAST BANK. 



Casper 1/2 - 67 



Wappinger 1/2 — 50 



Fishkill 6 - 40 



Sprout 3 — 8 



Peekskill 3 +10 



Croton _. 2 — 20 



* F. J. H. Merrill, The Geology of the Crystalline Eocks of Southeastern 

 New York, 50th Ann. Rep. N. Y. State Museum ; I. App. A. 21-31, 1898. 



\ C. P. Berkey, Structural and Stratigraphic Features of the Basal 

 Gneisses of the Highlands, Bull. 107, N. Y. State Museum, 361, 1907. 



