300 Review of Recent Geological Literature. 
ena of two unconformable formations that manifest constantly- 
distinct contrasts of stratigraphy and lithology. 
The theory of Foster and Whitney, that these ores are of 
eruptive origin, is opposed by chemicallaws, and by structural 
peculiarities that can not be reconciled with it. 
The ores of the Keewatin are markedly different from those 
of the Huronian in their chemical impurities. 
The theory of metasomatic substitution of iron oxide for 
somecarbonate,while applicable to the ores of the "Huronian" 
on the south side of lake Superior, cannot be made to account 
for the ores of the Keewatin, because, (1), There is no evidence 
of the existence, at any time, of the necessary earlier carbon- 
ate, and (2), The nature of the country rock embracing the 
Keewatin ore is such as to imply that no carbonates, in the 
amounts required by the theory, could have been deposited at 
the time the rocks were being formed. There is therefore 
necessity for some other explanation than that applicable to 
the "Huronian" ores. 
Chemical precipitation in hot oceanic waters, united with 
simultaneous sedimentary distribution, might produce the 
Keewatin ores in a manner consistent not only with the physi- 
cal conditions that prevailed at the time of their formation, 
and with the structural peculiarities which they exhibit, but 
also in accordance with the known reaction* of heated alkaline 
waters, and with the chemical character which the ores are 
known to possess. 
University of Minnesota^ August, 1889. 
REVIEW OF RECENT GEOLOGICAL LITERATURE. 
Solar heat, Oravitation and Sun-spotf. J. H. Kkdzie.* The author's 
vielv of the nature and cause of gravitation is derived directly from 
his theory of Solar heat, as already presented. Without rejecting, or 
even modifying, anything taught by Newton as to the laws of gravita- 
tion, Mr. Kedzie oflers a theory as to its cause and its mode of opera- 
tion. Newton did not discover its cause, nor attempt to explain its 
mode of action, but the great revelation that came to him referred only 
its law. 
The prevalent conception of gravitation gives every particle of mat- 
ter the power to reach out and draw every other particle toward itself. 
This idea the author not only questions but denies and disproves, and 
* See pp. 181, 240, for other portions of this review. 
