Rcviczv of Recent Geological Literature. 49 
In my correlation of the Baltic ridge westward with the 
British moraines of Lewis and eastward with the Valdai hills 
and the limits of plentifnl lakes in northern Russia, I differ 
from the mapping of DeGeer and Geikie. Instead of the 
southwestern boundary given for the "Baltic glacier" in the 
new edition (1894) of Geikie's "Great Ice Age," another mar- 
ginal moraine, which should probably be correlated with Dc 
Geer's Swedish boundaries of the Baltic stage in the glacial 
recession, extends, as I observed it, across the island of See- 
land (Zealand), passing northwestward from the ice-crushed 
hills of Riigen and Moen to Hammer and Njestved, thence 
northerly to the peninsula between the Ise fjord andRoskilde 
fjord, and thence northeastward to Flelsingcr (Elsinore), 
where it connects with the line traced by DeGeer across 
Scania, the southern extremity of Sweden. With this boun- 
dary we may, following DeGeer, correlate the more northern 
moraine which crosses the Wetter and Wcner, and his mo- 
raine on the island of Oesel, and the moraines of Finland; but 
these belong, according to the conclusions of this paper, to a 
kter recessional stage than the moraines of the Danish penin- 
sula and of Mecklenburg and Prussia, which are well named 
by glacialists as the Baltic ridge. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Geology of the Yukon Gold District^ Alaska. By Josiah Envv.'VRn 
Spurr. With an Introductory Chapter on the History aitd Condition of 
the District to i8Q7,V>y 'Hauq-lt) Beach Goodrich. (From the Eigh- 
teenth Annual Report, U. S. Geol. Survey, Part III, pp. 87-392, with 
plates 32-51, and figures 7-25 in the text. Washington, i8g8.) 
The field work on which this report is based was done in the sum- 
mer of 1896 by the author, with H. B. Goodrich and C. F. Schrader 
as assistants. The oldest rock formation in the gold region is granite, 
usually more or less schistose or gneissic, and sometimes passing into 
mica schist. Next in ascending order is the Birch Creek series, 
roughly estimated as possibly 25,000 feet thick, consisting mainly of 
quartzitic rocks, generally thin bedded or schistose, with abundant 
quartz veins, which carry gold with pyrites and sometimes galena. 
Above the Birch Creek series, and in general closely associated with 
