-••i .\i;\\ VuliK STATE ml'si:l\m 



a irt'iich of Ilia I lt'n«j;ili 1 iiiilc widi^ and GGO feot deep. Of 

 course siicli an arillnnetieal calculalion is solely intended to 

 show that enonj^h material has been transferred in the Uudson 

 vallcv since the «i:lacial i)eriod to more than till to its present state 

 an old jiorge smh a« the elevation hypothesis supposes to have 

 existed. 



As we have no direct evidence that the Hudson gorge is so 

 deeply excavated in the bed rock from AN'est l*oint sonthward 

 through the New York NaiTOws the question of altitude of the out- 

 let at this ])articular stage under the conditions assumed must 

 remain locally undetermined. 



The width of the Narrows at the present sea level is approxi- 

 mately 1 mile and the banks are glacial materials. There is 

 naught in the deposits at the Narrow's to render a former deeper 

 channel impossible. In fact, if we suppose the sides of the 

 channel where it is narrowest to slope dow^n at an angle no 

 steeper than 30 degrees the slopes would meet at a depth of 

 over 1500 feet below the present sea level, a depth much in 

 excess of any required depth of the Hudson channel for the 

 drainage of waters from the Hudson-Ohamplain valley under 

 any of the conditions which are shown to have existed during 

 the retreat of the ice sheet. 



From a reference to the diagram plate 28, line G-H, it will be 

 seen that the outlet of the Fort ICdward stage of Lake Vermont 

 at New York must now be submerged not less than 650 feet if the 

 view taken on page 102 is correct. 



DEFORMATION BY POSTGLACIAL FAULTS 



From the vicinity of Greenbush northward into Argyle there 

 is a belt of as yet unknown width in which the glaciated surfaces 

 of nearly vertical slates are disrui)ted by small faults with a 

 downthrow on the west, showing that in j)ostglacial times the 

 land on the western side of the Berkshire hills has come to stand 

 relatively higher than that in the Hudson gorge and on the west 

 of the river. Further detailed work in the field is required to 

 make a quantitative statement concerning the amount of movement 

 on Ihese small faults. I have not been able without this detailed 

 study to determine what role they may have played, if any, in 



