. 
114 Scientific Intelligence. 
Conocardium trigonale, Atrypa reticularis, Favosites polymorpha, 
Hamilton with Spirifer mucronatus, &c. 
little lakelets or sphagnous marshes so characteristic of the region 
referred to. These are the beds to which I have alluded as constr 
glaciers but by icebergs. : 
“ Possibly some part of this Drift material may have accumulated 
along the margin of the great glacier, moved by its agency ; se 
nts 0: 
the boulders, for the most part come from some remote point at the ; 
North, and were once spread broadcast along the southern shore 
of the inland iceberg-bearing sea. 
highest lake level of former times, 7. ¢., all within a vertical height 4 
of more, in turn have been submitted to the 
action of the shore waves, and rivers, by which if, as is prob- 
ble, the retrograde movement of the water line was slow, these 
materials would d, ground, sifted and shifted, 
e fine materials, clay and sand, would be washed out and carried 
farther and still farther into the lake basin, and spread over the 
bottom, to form, in short, the upper sand layers of the Drift.” 
. Newberry closes with remarks on the origin of the great 
lakes, in which he states his conclusion that : 
“1st. Lake Superior lies in a synclinal trough, and its modeof = | 
formation therefore hardly admits of question, though its sides > 
are deeply scored with ice-marks, and its form and area may have 
been somewhat modified by this agent. | 
“2d. Lake Huron, Lake Michigan, Lake Erie, and Lake Ontari®, 
are excavated basins wrought out of once continuous sheets of 
sedimentary strata, by a mechanical agent, and that ice or wate! 
os both. ; 
