ANCIENT WAfER LEVELS OF CHAM PLAIN— HUDSON VALLEYS 127 



above sea level. Its contact with the overlying clays was nowhere 

 well exposed at the time of my visit. 



The top sands appear to follow the clays naturally as the result 

 of shoaling water and the pushing out of the ancient delta of 

 Rondout creek. It is noticeable that the sand beds have been cut 

 out from time to time to the depth of 3 or 4 feet and as rapidly 

 filled in by the continued transportation and deposition of sands 

 from the same general source. The dominant cross-bedding in 

 these sands displays a southeastward dip, but sections are ex- 

 posed in which the opposite direction may be observed, from which 

 it is to be inferred that the currents which carried the sand were 

 subject to changes in direction. The almost complete absence of 

 pebbles in this deposit is indicative of weak bottom currents at 

 this level and as well the want of floating ice by which such coarse 

 particles are often distributed. 



Rondout terrace deposits. One sees two terrace levels about 

 Rondout. A lower one is very well marked north of the ferry 

 landing at about 50 feet above tide, the higher one occurs at 

 200 feet. A trench 4 feet deep in fine sand was exposed at the 

 time of my visit at 51 Abruyn street near East Union street on 

 the 50 foot terrace. This lower terrace is so much built over that 

 its precise nature is in doubt. Toward the rock cliff and just 

 north of the old cement quarry drifts, sand, composed in part of 

 white quartz grains and hard shale bits, occurs as high as 100 feet 

 and fragments of probably the same deposit rise to 120 feet. 



Toward the north the 200 foot terrace shows gravel under the 

 clayey sand of its upper section. So far as I was able to observe 

 the clay is wanting in the immediate vicinity of the mouth of 

 Rondout creek on the north ; but at Kingston Point the clay ap- 

 pears and just south of the Terry hill triangulation station ex- 

 tensive clay banks have been opened. 



In the Hutton Co.'s yard there is a topping of from 35 to 40 

 feet of sand, sometimes cross-bedded, with dip of cross^beds to 

 the northeast. A lower part of this sand may fairly be described 

 as clayey sand, pointing to a gradation into the purer clays 

 beneath. 



The clays are blue, with fine, white, micaceous sand bands vary- 

 ing in thickness from *4 inch to 1 inch or even thicker. Thin 



