GLACIAL LAKE LUNDY AND TRANSITION TO LAKE ALGONQUIN. 407 



TRANSITION TO LAKE ALGONQUIN. 



When the waters fell to the level of the Lundy beach they were barred by the Port Huron 

 moraine (here a single, simple, smooth ridge), a mile north of the village of St. Clair (as shown 

 on fig. 10), until they could cut a short, shallow channel through it. (See p. 474.) This was 

 done quickly, for the beach was made south of the barrier as well as north of it. Hence, after 

 cutting through the moraine the lake waters soon came to one level on both sides of it and stood 

 in that position while the Lundy beach was being made. 



This stage of the waters might be regarded as the beginning of Lake Algonquin, but such 

 was clearly not its real relation. The lake at the time of the Lundy beach was simply a lower 

 stage of Lake Lundy. The uncovering of a barrier between Lake Huron and Lake Erie, through 

 which the waters found it necessary to cut a channel, makes this stage technically transitional 

 between Lake Lundy and Lake Algonquin. While the first or higher channels were being cut 

 through the barrier the waters in the Lake Erie basin stood a few feet lower, and although this 

 condition lasted only a very short time, it separated the Huron-Erie waters into two bodies 

 with their surfaces at different levels. The moraine, however, was not able to hold the waters 

 against the eroding power of the river long enough to make shore lines at different levels on the 

 two sides, so that the Lundy beach marks the lake surface as the waters stood after the first 

 channels had been cut and the waters had come practically to one level. 



After standing for a time at the Lundy beach the waters fell to a lower level, probably on 

 account of the withdrawal of the ice from the escarpment south of Syracuse and the opening 

 of a lower outlet. This renewed the channel cutting through the Port Huron moraine at St. 

 Clair and soon inaugurated the cutting of a similar channel through the interlobate moraine at 

 Detroit and through another barrier at Trenton. (See pp. 476, 485-492.) All of this channel 

 making from the first cutting through the Port Huron moraine was done by a river flowing 

 from north to south — that is, from the basin of Lake Huron to the basin of Lake Erie — and the 

 fall of the waters from the Lundy beach resulted in the final separation of the lakes in the Erie- 

 Ontario basin from those in the Huron basin. The cutting on the Trenton barrier soon passed 

 the rapid stage and became very slow. The barriers at St. Clair and Detroit were soon cut 

 down to a low grade with reference to the Trenton barrier, and then a relatively stable state 

 for the connecting rivers and for the lake above was established. This was the beginning of 

 Early Lake Algonquin. 



There are one or two other remote alternatives as to the precise order of events at the be- 

 ginning of Lake Algonquin. An outlet to Lake Chicago or to Lake Simcoe and the Trent Valley 

 may possibly have occurred before the morainic barrier at St. Clair was uncovered, so that when 

 the waters fell to the level of the barrier's crest, there was no tendency to overflow toward the 

 south or to make a channel through it in that direction. But even then, unless there were at the 

 same time an eastward outlet for the waters in the Erie-Ontario basin, the discharge of those 

 waters would have had to pass northward across the barrier and would have cut channels in 

 that direction. But the first flow over the moraine left a clear record in distributary channels 

 which prove absolutely that the flow was southward. 



If, perchance, outlets were opened both to Lake Chicago and near Syracuse at the same 

 time, so that the moraine at St. Clair might be uncovered without making a channel across it 

 in either direction, this barrier might have been left unbroken. Then later, when the waters 

 on the two sides came to have different levels, it is perhaps conceivable that the barrier held the 

 waters in one of the basins at a higher level than they would have maintained had the barrier 

 been broken. Indeed, it is necessary to believe this if Spencer's opinion that Lake Algonquin 

 had no southward outlet be accepted. But against this view, the distributaries (see fig. 10) 

 show plainly that the first flow over the moraine was southward at. a level a few feet higher than 

 the Lundy beach and also that the channel was not made by a small stream but by a river of 

 great volume. These facts seem to make the last two alternatives untenable. Indeed, if the 

 last alternative is accepted St. Clair and Detroit rivers could have come into existence only by a 



