646 CHARLES EMERSON FEET 



system was tributary to the Raritan, which, presumably, was tributary 

 to the Hudson. The connection of the submerged Raritan and 

 extra-morainic Hudson channel, however, cannot now be traced. 



4. Scarcity of wave-wrought features in the Hudson Valley. — The 

 almost complete absence of wave-wrought terraces in the area of the 

 Hudson water body south of Glens Falls is not what would be expected. 

 Even faintly developed terraces have been observed at a few places 

 only. This apparent lack of effective wave-action may be due to 

 the following: 



(i) In the presence of the ice-sheet the water body was frozen 

 over for considerable periods of the year, and during the summer 

 season the presence of floating ice would tend to reduce the effective- 

 ness of the wind in producing waves. This explanation would apply 

 on either hypothesis for the origin of the Hudson water body. It 

 would be more applicable if the body was a lake, but would apply if 

 the water body was the sea, and if much freshened as suggested 

 below (p. 650), it would be nearly on a par with the action in a lake. 



(2) After the ice-sheet had retired to the northern part of the area, 

 these conditions would no longer exist or would be much weakened in 

 their effect and wave-action would be expected, (a) It is to be noted 

 here, however, that the southern part of the area is the narrow part 

 where the wind would have comparatively little chance to produce 

 effective waves, even under the most favorable conditions of tempera- 

 ture. The greater width of the water body in the northern part of 

 the Hudson would seem to necessitate effective wave-action after 

 the ice retired into the Lake Champlain region and the climate had 

 become warmer, so that the surface was no longer frozen over for 

 so large a part of the year. Too much emphasis, however, must 

 not be placed on the warming up of the climate, for boreal willows 

 in the Salmon River section indicate a climate considerably colder 

 than the present in Marine Champlain time, {h) It is to be noted, 

 also, that this wide northern part of the Hudson water body was 

 divided into smaller portions by numerous islands and shoals (see 

 Fig. 13, p. 437), and these would decrease the efficiency of the wind 

 in producing waves, (c) If this water body disappeared shortly 

 after the ice had reached the Champlain valley, the length of time 

 for this effective wave-action was reduced, and the earlier the dis- 



