04 REVIEWS 
There were two periods of lake development. During the inter- 
vening epoch the first deposit was almost cut through. The two stages 
of filling are now marked by terraces, the later of the two being ro feet 
to 20 feet lower than the first. 
The older of the two stages is younger than the Illinois till—prob- 
ably of late Illinoian age. The other is ‘‘in or near Wisconsin time.” 
ERs 
The Ellamar District, Alaska. By S.R. Capps and B. L. JOHNSON. 
Wiss Geol sunvey- Bull! No. 6055 Toms) =Ep. «250 pisses 
figs. To. 
Previous writers have considered that the copper deposits of the 
Prince William Sound region are genetically related to basic lavas, 
being formed either as concentrations of disseminated copper minerals 
of these greenstones or in connection with basic intrusives. The 
deposits are in shear zones along fault planes, principally in the green- 
stones. The ores carry, besides copper, some gold and silver. The 
minerals are chiefly sulphides, chalcopyrite, pyrrhotite, and pyrite 
predominating, with smaller amounts of sphalerite, galena, and arseno- 
pyrite. The ore minerals cement or replace the shattered country rock. 
Quartz-filled fissures carrying similar minerals are less common. The 
evidence obtained indicates that the deposits were formed by primary 
sulphide impregnation along the fracture zones by rising magmatic 
solutions. Both the gold and copper veins of this region are believed 
to have been formed during a single period of mineralization closely 
following and genetically related to the late Mesozoic granitic intrusives. 
HRB: 
Mineralogy, Crystallography and Blowpipe Analysis, 5th edition. 
By Moses and Parsons. New York: Van Nostrand & Co. 
(1916). Pp. xiiti+631, figs. 575. 
The new edition has been expanded by the addition of new economic 
groups, by the discussion of origin and association of minerals, by added 
discussion of crystal optics, and by new determinative tables. The 
economic basis for classification is retained and emphasized, though 
many minerals of no economic importance are included. Perhaps the 
greatest difficulty arising from this classification is in the breaking up 
of customary crystallographic groups. For example, the rhombohedral 
carbonates must be sought out by looking through the calcium, mag- 
