GLACIAL WATERS IN BLACK AND MOHAWK VALLEYS I9 



MOHAWK VALLEY GLACIAL WATERS 



FIRST STAGE : EARLY ADIRONDACK DRAINAGE 



In describing the outflow of the Black valley waters reference 

 was made (page 12) to deltas built at Trenton by the Remsen river 

 and north of Rome by the upper Mohawk. These deltas are too 

 massive to represent local and transient lakes held in embayments 

 along the edge of the glacier, and their position and relation to the 

 ice front and to the open valley forbid the assumption. The 

 ice front here was a lobe pushing in from the west. The deltas lie 

 on the north border of the broad Mohawk valley and were evi- 

 dently deposited in broad waters which flooded the Mohawk and 

 extended far east. The existence of other high-level lake deposits in 

 the Mohawk valley has long been known, terraces and level stretches 

 being conspicuous at intervals from Utica to Schenectady. The 

 waters were ice-dammed. The Hudson valley ice lobe blocked the 

 valley on the east while the Ontario ice lobe blocked it on the west. 

 With the knowledge already gained concerning the positions of the 

 receding ice fronts, the impounded waters and the inclosing topo- 

 graphy, the conclusion is imperative not only that the Mohawk valley 

 held glacial waters but that they were sustained at different levels. 



In the waning and thinning of the ice sheet which overspread 

 central and northern New York there must have been a stage when 

 only a neck or strait of ice rested in the Mohawk valley, connecting 

 the Hudsonian and Ontarian lobes of the Laurentian glacier. The 

 earliest glacial waters of the Adirondack region must have gathered 

 in the valleys along the southern slopes of the highlands and resting 

 against the margin of the ice in the Mohawk valley. The only 

 escape for these waters was southward across the Mohawk ice at 

 its lowest point (see discussion of this matter in the introduction). 

 The sand plains in the Adirondacks at high levels probably belong 

 to this time. Some of the water deposits were probably accumulated 

 in restricted waters, held by local glaciers or by tongues of the re- 

 ceding ice sheet which surrounded the exposed highlands ; but the 

 ultimate escape of the waters must have been to the south and over 

 the belt of stagnant ice which lay in the Utica-Little Ealls section 

 of the valley. 



The early removal of the ice sheet from the Adirondack highlands 

 and the consequent existence of high-level glacial waters in the 

 mountain district has been recognized by F. B. Taylor (see title 36). 

 He noted terraces and sand plains in the Saranac valley at 1370 



