64 Scientific Intelligence. 
related to that given by Professor N. H. Winchell, in his Minne- 
sota Geological Report for 1876, (published in 187 7)* and that the 
hills of the granitic =. stretching sacar aie from 
Keweenaw Point, and from the south shore of Lake Superior 
farther west, prevented the Spasaasie of shes great glacier from 
Lake Superior i in that dire 
Both Professor Chamberlain and Professor Irving state that 
there is abundant evidence that during the Glacial era the continent 
in that part was higher above the sea-level than now; and that 
this elevation was followed by a depression below the present | level 
—that of the Champlain period. The former states that “some 
of the streams have cut channels from one to three RE feet 
deeper than those they now rola DASE oy pointing to the fact of 
greater elevation during the Glacial e 
The chapters on the drift contain numerous facts with regard 
ba the sources of the — proving ee coe for 100 to 300 
The observations on the Champlain deposits and terraces are also 
highly interesting. 
wo other facts we cite here. The Milwaukee brick have 
a cream-white color and this has been attributed to the absence 
of iron. But Professor Chamberlain states that the clay is red, 
and contains, according to analyses of the brick, nearly jive per 
cent of oxide of iron; and that the absence of color must be due 
to the formation of a silicate of lime and iron, lime being also 
present in the ¢ [The eee. is probably a variety of epee, 
the formation of Which 3 in the Triassic red sandstone of the Con 
necticut valley where it adjoins "Ses dikes has often been oleckvad 
the writer to be connected with a discharge of the red color 
of the sandstone. 
The Niagara fimestone of southern Wisconsin includes two 
distinct varieties of limestone which were of simultaneous origin; 
and, according to Professor _ Chamberlain, sa "oe ah kind 
ral reef seas, 
and the granular to the beach sand-rock, sik is ations 
made along the shores of the coral reef regions out of — sands. 
. D. De 
Jo 
+ Mr. A. H. Wo rthen states, in the first volume of hie palace rhe , of 
i pean to 
oelow Galena within the driftless area but not far north of its southern limits) he 
observ: . Beebe informed 
in Lucas county, near the middle of southern Iowa, which weighed more than 
beg pounds. Galena is about 350 miles ina straight line south southwest from 
sl an era w copper region, and Lucas county is 170 miles southwest-by-west 
arom Cralens, or about 465 miles southwest-by-south from the Keweenaw region. 
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