452 FRANK BURSLEY TAYLOR 
The great Malaspina glacier of Alaska, so well described by 
Professor Russell, belongs to the Piedmont type, and is probably 
suggestion: “That a series of terminal moraines in a formerly glaciated valley, or a 
similar succession of ridges left by a continental glacier, are not necessarily evidence 
of repeated climatic oscillations, but may have been formed during a uniform and 
continuous meteorological change favorable to glacial recession. ‘That is, a débris- 
charged glacier may retreat for a time, then halt and again retreat, owing to its termi- 
nus becoming congested with foreign material, in response to a climatic change which 
would cause a glacier composed of clear ice to recede continuously and without halts.” 
It is hard to see how clogging of the lower layers could have the effect of build- 
ing a ridge like a terminal moraine anywhere except at or very near the edge of the 
ice-sheet; and it seems certain also that the building of a great moraine must have 
required a relatively long duration of time—much longer than the building of the 
flat intermorainic plains of till. But under a uniform change of climate, as supposed 
by Professor Russell, it seems impossible to allow much more time for the building of 
a moraine than would be taken by a clear-ice glacier to retreat over an interval equal 
to the width of the moraine unless the formation of the moraine is supposed to begin 
under deep ice far back—at least several miles back —from the edge of the lobe. 
When the front of the Maumee ice lobe was at Fort Wayne the ice was probably 400 
or 500 feet thick within a mile or two back from the edge, and its thickness increased 
to the northeast. From Fort Wayne to Port Huron there are five moraines in series 
with four intervals of about fifty miles each, and with wide till plains intervening. 
When the ice-front was just east of the Fort Wayne moraine, did basal clogging begin 
then at Defiance, forty-five miles back under the deep ice, or did the ice-front retreat 
from Fort Wayne to Defiance without clogging only to begin it again at the latter 
place? If the former, then we must set aside the law of heavy abrasion on subglacial 
prominences under deepice. Ifthe latter, then, as already pointed out, the time allotted 
for the building of the moraine is little if any longer than that which would be taken 
by a clear-ice glacier to retreat over a distance equal to the width of the moraine. 
The Port Huron-Saginaw moraine is clearly traceable as a distinct individual 
from the highlands south of Georgian Bay, where it is about 1000 feet above the 
lake, descending to lake level at Port Huron, rising thence 300 feet to Ubly on the 
“thumb” of Michigan, descending again to lake level at Saginaw, rising again 
towards the northeast to the Au Sable River, and thence northwest nearly as far as 
Petoskey, where it is again about 1000 feet above the lake—a distance of over 400 
miles. It seems hard to account for such a moraine by clogging alone, and fora 
series of them, the existence of which is a matter of simple inference from the facts 
now at hand, the difficulty becomes much greater. Speaking of the terminal moraines 
of the United States, Professor Chamberlin says: ‘‘Some of these have been traced 
several hundred miles in individual distinctness, and, by fair correlation, may be 
assumed to have been identified for a thousand miles or more.” (GEIKIE’s “ Great 
Ice Age,” 1894. p. 740.) 
But even if basal clogging in itself could produce moraines, that process taken 
alone could hardly be the cause of such a marked and widespread periodicity in the 
phenomena. The continuity and great length of individual moraines shows that the 
periodic rhythm of the oscillations affected wide areas ; indeed, there lacks but little to 
