MORAINES OF RECESSION 445 
certain evidence they have adduced that lobes ending in glacial 
lakes broke up like calving fiord tongues and floated away so 
rapidly as to make their fronts concave.'’ Chamberlin seems to 
show this effect by two moraines in the basin of Lake Agassiz 
on his map in Geikie’s Great Ice Age, 1894 (opposite page 727). 
Whatever the facts may be for the Lake Agassiz basin, this was 
certainly not the case with the Huron-Erie lobe. The fact that 
the ice was able to keep its place in 200 feet of water almost as 
though no water were present shows (1) that it was not broken 
and deeply crevassed into loose blocks that might easily float 
away, but was comparatively solid and compact, proving (2) 
that its motion must have been of the slow order rather than 
of the rapid; (3) that its thickness at the edge as it then 
existed must have been considerably more than 200 feet, prob- 
ably not less than 300 or 400 feet ; (4) that although the front 
must have been undercut and broken off to some extent by wave 
action, flotation, and melting in the lake water, this process did 
not become a factor of sufficient importance to seriously 
disturb the line of the ice-front as determined by land relief 
alone. The Saginaw lobe shows the same ability to conform to 
the land relief while standing in water at the Saginaw moraine 
over 150 feet deep.? I am led to believe, therefore, tentatively, 
that the motion of the ice-sheet while building the moraines of 
recession was very slow. That is, it was so slow that the lobes 
as they crept along remained essentially solid to their extreme 
edges. 
*Glacial Lake Agassiz, Monograph, by WARREN UPHAM, Plates XVII and XIX. 
Pleistocene History of the Champlain Valley, by S. P. BALDWIN, Am. Geol., Vol. XIII 
March 1894, p. 181. 
?Nansen, in his “ Farthest North,” Vol. II, p. 339, describes a glacier-front of 
this kind in Franz Josef Land in the following terms: ‘‘ We were soon underneath 
the glacier, and had to lower our sail and paddle westward along the wall of ice, 
which was from fifty to sixty feet in height, and on which a landing was impossible. 
It seemed as if there must be little movement in this glacier; the water had eaten its 
way deep underneath it at the foot, and there was no noise of falling fragments or 
the cracking of crevasses to be heard, as there generally is with large glaciers. It was 
also quite even on the top, and no crevasses were to be seen. Up the entire height 
of the wall there was stratification, which was unusually marked.” 
