198 The American Geologist. Marcii, i89i 
different altitude above the sea. There are five of the upper beaches, 
viz : The Herman beach which becomes separable into seven stages, the 
Noreross beach which has two stages, the Tiutali beach, with two stages, 
the Campbell I>eac1i, with three, and the McCauleyville beach, with three 
stages. These upper beaches were all formed while the lake out-flowed 
southward at lake Traverse, by way of the valley of the Minnesota river 
to the Mississippi valley. They are traced through Minnesota, 
Dakota and Manitoba. There are lower beaches, formed by lake 
Agassiz at a lower stage, and while the water found escape northward — 
though by what channel or channels it is not certainly known. These 
lower beaches exhibit a similar ascent toward the north indicating some 
progressive change in the earth's crust which continued during the 
whole existence of the lake. 
The waters of lake Agassiz rose above the present level of lake 
Winnipeg about 600 feet during the upper Herman stage, 500 feet during 
the upper Norcross stage, 440 feet at the upper Tintah stage, 370 feet at 
the upper Campbell stage, and 325 feet at the upper McCauleyville 
stage. During the lower stages of the lake, while* the discharge was- 
northeastward, the depth of lake Agassiz above lake Winnipeg decreased 
to 285 feet at the upper Blanchard stage, 240 feet at the Hillsboro beach, 
210 during the formation of the Emerado beach, and finally 65 feet at 
the time of formation of the lowest or Niverville beach. The lake ex- 
tended northward during its greatest development, to the divide lying 
on the south side of the English or Churchill river, that is to lat. N. 55o 
with along westward arm which ascended the Saskatchewan valley. On 
the international boundary it extended to the east end of Rainy lake and 
thence turned abruptly northward, its northeastern limits being wholly 
unknown, but probably coterminus with the ice-sheet that caused, 
nurtured and perpetuated it. 
The Geological and Natural History Survey of Minnesota, Eighteenth, 
annual report, for 1889. N. H. Winchet.l, state geologist. 234 pages; 
11 figures in the text. (Minneapolis, Minn., 1890.) About 60 pages of 
this report present notes of field observations during 1888 and 1889 by 
the state geologist, in the iron-producing district of northern Minnesota, 
in the vicinity of Pokegama falls, in the valley of the Minnesota river, 
and in the area of the original Huronian rocks north of lake Huron and 
Georgian bay. The author concludes that the Huronian system, as that 
term is now defined and used in the Canadian geological reports, com- 
prises three' separate formations, namely, in descending order, (1) the 
true Huronian, as first described and mapped by Murray; (2) the 
Keewatin, discriminated and described by A. C. Lawson in the region of 
the Lake of the Woods, to which are referred the rich iron ores of 
Tower, Minn.; and (3) the Vermilion series of crystalline schists. 
These formations are stated to be distinctly separated by lithologic 
differences and by unconformities that have been noted from Vermont 
to Minnesota, so that they should no longer be classed together without 
