2'he Second Lol-e Al(imi<jiiii}. — Taylnr. 179 
tory. The cause of these great changes is at present veiled 
in obscurity. Above the level of the Nipissing beach there 
are other complex series of shore lines. In the south they are 
undoubtedly referable to ice-dammed lakes of the glacial re- 
cession. But those of the south are not connected with those 
of the north, and in the north, where they are highest, there 
is no evidence of any relation to an ice-dam. For lake Algon- 
quin in particular there is not the slightest indication of any 
relation to an ice-sheet, and there is no possible ground or 
excuse for such a supposition. All their stages and deforma- 
tions are more plausibly accounted for in other ways. 
Much 3'et remains to be done, especially in the way of sjj-s- 
teraatie exploration, before the complete postglacial history 
of the Great lakes can be written. But this sketch of the his- 
tory of lake Algonquin is offered as a small and necessarily 
imperfect contribution to the study of the recent history of 
the Great lakes, and in general, of Pleistocene changes of land 
attitude in eastern North America. 
Explanation of FIGURE^^. 
Fig. 1. Diagram sliowhiii' rolations of Hit- Nipissiiii;- and Sault bcaclics 
to each other ami to the SiHM'rior and Huron planes. In tin- \crtical 
scale llie Huron ])laMe is taken as zero. The Sault beaeh is confined 
I'nlirely to the Superior basin, and marks the last bench made by lake 
Superior before the jireat eastward or Champlaiii uplift which lilted the 
Nipissini;- plane. 
Fig. 2. (After S]»encer, modified.) Cross-sections of Xiaiiara uorue: 
(", g'orore of Whirlpool rapids, just below the railroad bridji'es; !), at .lohn- 
son's rid<;e, about a mile above the bridiie: .-mil K, at Horseshoe fall. .\t 
the top, ill the Niaffara limestone, section (' is iibout half the width of 
DorE. Section C was made by the Erijran fall. The Inupiois beach 
( i:{.") feet above lake Ontario at Tjewiston) was made by the sea at the 
same time, and it represents its level as the water stood in the Erinan 
jrorfie; hh, i)robable rock bottom of Erigan gorge, represented as '") feet 
Ix'low i)resent surface of rapids: /■ /•. the present rixcr surfaci'. 
Fig. 3. (.Vfter Spenci'r, modified.) This figure is intended to show 
the probal)Ie longitudinal section of the gorge from the Horseshoe fall 
to a point a little below the Whirlpool. It shows the Erigan gorge 
shallow and with bottom inclined. The depth of water at the fool of 
the Erigan fall is to be measured from the Iroquois level, Mud was 
therefore probably about two-thirds as deep as the ])resent pool at the 
falls. 
