570 The American Naturalist. — [June, 
Zaleski’ has made, with great care, a number of chemical analyses 
and mechanical separations of several granites to determine whether or 
not they are syenites plus quartz; that is, whether or not the chemical 
limits between which these rock types vary are fixed. His results 
may be tabulated as follows: 
Locality. SiO, Content. SiO, of rock—Quartz. 
Dannemora, 61.06 ; 
Nigg, 69.84 65.33 
Hangö, 71.42 59.46 
Baveno, 74.44 41.38 
Of these granites only one possesses the silica content of syenite after 
the sor he has been abstracted from it. 
Spurr,’ in a bulletin on the iron-bearing rocks of the Mesabi Range in 
Minnesota, describes a series of fragmental and cherty rocks associated 
with the ores. One of these, to which he gives the name “taconite,” 
consists of a groundmass of silica, in which are granites of a green 
substance, regarded by the author as glauconite. These are always more 
or less altered, yielding siderite, magnetite, hematite, etc. The sideritic 
phase of this taconite is like the original carbonate of Irving and Van 
Hise. 
In asmall collection of specimens from central and western Para- 
guay, Milch’ has recognized quartzites, limestones and phonolites. 
GEOLOGY AND PALEONTOLOGY. 
Niagara and the Great Lakes.—Another contribution to the 
history of the Great Lakes is published by F. B. Taylor.” It is the 
eighth of a series and brings the history up to date. In an introduc- 
tion the author refers to the recent papers of Professor J. W. Spencer 
and Mr. Warren Upham on the post-glacial history of the Great 
Lakes in the following language :— 
“ Prof. Spencer on the one hand levels all the higher abandoned 
beaches with the sea, and does not distinctly recognize a single ice- 
1 Ib., XIV, p. 342. 
ê Bull. No. X, Geol. and Nat. Hist. Survey of Minn. 
? Min. u. Petrog. Mitth., XIV, p. 383. 
1 Amer, Journ. Sci. Arts, 1895 
