ANCIENT WATER LEVELS OF CH A MPLAIN— HUDSON VALLEYS 07 



over New England and westward over the Highlands of New 

 Jersey. In the retreat from the terminal moraine however it is 

 to be expected that the lobate form of the ice in the lower Hudson 

 would be retained, and since the axis of the lobe lay in the low- 

 lands west of the Palisade ridge the east margin of the lobe in its 

 retreat would first uncover the east bank of the Hudson from New 

 York city northward and then the western bank of that river. 

 This relatively earlier opening of the east bank of the river would 

 permit of the drainage from the open country in Westchester 

 county pouring in against the ice margin so as to make deposits 

 partly built against the ice either within the open parts of the 

 gorge or within the dissected rock terrace itself. On the contrary, 

 on the west bank no such deposits would occur, largely because 

 of the lack of an open land slope toward the Hudson. 



In this lower section of the Hudson the stratified glacial 

 deposits are restricted to the east bank in situations suggesting 

 in their form and distribution their constraint by the ice margin. 



The slight mounding of the deposits at the head or ice contact 

 of the outwash plain at Englewood and again near Tappan vil- 

 lage show that the ice at these stages of retreat was slightly 

 quickened and advanced on its frontal outwash deposits, move- 

 ments which would have extended to the eastern margin, account- 

 ing for some distribution there of till over stratified deposits and 

 a slight shoving of stratified beds into disturbed positions. 



This inequality of the distribution of stratified deposits is 

 shown elsewhere as on the banks of the Taunton river near Fall 

 River, Mass., where stratified drift, locally a kame terrace, flanks 

 the south side of that southwesterly trending arm of the sea while 

 till without signs of water modification covers the other bank 

 quite down to sea level. 



The rule in such situations is that when the ice is retreating 

 with its front nearly or quite parallel to a river valley the bank 

 which is first uncovered by the ice will receive outwash from the 

 ice and inwash from the confronting land while the opposite bank 

 may be left strewn with the ill assorted or unstratified boulder- 

 bearing drift dropped by the ablation of the ice. On the open side 

 of the valley, terraces and kame terraces may thus be formed at 

 levels independent of the sea but above its level. 



