Geology and Mineralogy. 155 
earliest time when land began to exist from the conditions of 
ae light on this subject could be procure 
didcrea by Professor Whitney, nor those by which a@ warmer 
cean—from whose area would come warm winds as well as exces- 
sive Phigss bapor pallies bie gc the extensive glaciation of which 
there is abundant record even in California and Colorado as well 
as in other colder prstesid The argument for narrower limits to 
the glacial regions eee ee been laid down, which for North- 
eastern America is ma more of supposed reasons for doubts 
than of positive facts at. conmoral observation, can be best met by 
present the results of a wud of the “ New Haven region” in an 
early number of this Jou 
The author does “ ey ae r Dana” much more than justice in 
the remark that “his authority is almost exclusively mates ed by 
the younger workers in Geology in this country ;” for, in connec- 
tion with this subject of the Glacial era, the various State e geolo- 
gists, younger or Pee par head knowledge and judgment en 
Pennsylvania and other States, to Minnesota. Professor Whitne 
points out that the writer has greatly changed his opinions with 
the progress of the science by quoting, in a note referring to his 
recent views, the views he held in 1863. The writer is open to 
further changes of opinion whee ew facts may require them; 
and he will have some to present in the forthcoming suey 
3. Tenth Annual Report of the cans lage and Naan His. 
| 18 ie ec Bs a 
eh wie Aster (2) the ghee dese ‘ed horizontal sandstones ply the 
south shore of Lake Superior n Wisconsin, holding Fucoids 
and Scolithuss and (8) the St. Cr roix sandstone sontataiag Lin- 
gule and Trilobites 
After a comparison of the rocks and their fossils with those of 
the Potsdam and Caléiferous of the Eastern i pis States, he 
ar 
