BETHLEHEM MORAINE 273 



ton (as shown in plate 13), would dam the Ammonoosuc River, holding 

 it up to a level approximately the altitude of the moraine summits; for 

 there is no outlet above Wing Road lower than the 1,320-foot pass just 

 south of Bethlehem Junction; and even this would hardly appear to have 

 served, inasmuch as the ice at the time it lay against the Bethlehem 

 moraine would probably have dammed up the lower part of the Gale 

 River- South Branch system below Franconia. Indeed, as the map shows, 

 morainic belts similar to those seen by Agassiz and in fairly definite 

 alignment with them extend from the eastern side of the Ammonoosuc 

 above Wing Road in an easterly or northeasterly direction, indicating 

 that during this stage the river was blocked. Among these moraines are 

 three sharply defined hillside ridges, which run obliquely up the slope of 

 the 1,612-foot hill east of Wing Road, resembling the moraines described 

 by Taylor in the Berkshire Hills. 15 There are also broader belts of sag 

 and swell topography. Blocks abound on most of these, save where they 

 have been removed in cultivating the fields and built into stone walls; 

 and stratified drift, while not unmixed with till, is the dominant type of 

 deposit. 



TREND OF THE MORAINE 



The map, although not as complete as it may be made by further field 

 work, shows the location and trend of the more definite lines of moraine. 

 The full width of the belt, it will be seen, is 2 miles. It obviously bears 

 no relation to the Mount Agassiz saddle or to any local glacier from the 

 south. Such glaciers would be comparatively narrow, and would deposit 

 moraines whose curvature was convex northward, where they terminated, 

 fanlike, on the lowland. The local curvatures of the Bethlehem moraine, 

 which are slight in every case, are definitely convex southward. The 

 moraine therefore cannot be assigned to local glaciers moving northward. 

 As Upham discovered, it marks the border of an ice-sheet. His state- 

 ment, however, that this moraine runs continuously eastward up Am- 

 monoosuc Valley to Twin Mountain House is inaccurate. While there 

 are morainic deposits east of Maplewood, south of Bethlehem Junction, 

 and around the Twin Mountain House and at Carroll, these are so far 

 out of line with the moraines east of Wing Road that they pretty surely 

 mark different stages of retreat. 



The trend of the morainic lines, it will be seen, is perpendicular to the 

 course of the strias, as shown by arrows on the map, which are based on 

 observations of Hitchcock, with some additions. While the strise them- 

 selves do not indicate whether the movement was northward or south- 



15 F. B. Taylor : The correlation and reconstruction of recessional ice borders in Berk- 

 shire County, Massachusetts. Journ. Geol., vol. 11, 1903, pp. 323-364. 



