376 REVIEWS 
equal of some of the high-grade eastern coals, or some of the coal from 
the Alaskan fields. The careful studies which have been devoted to the 
geological and commercial problems connected with the King County 
coal fields are well set forth in this bulletin. 
Ree 
Geology and Ore-De posits of the Nizina District, Alaska. By FRED W. 
Morrit and STEPHEN R. Capps. Bull. 448, U.S. Geol. Survey. 
Pp. 108; pls. 12; figs. 11. Washington, D.C., ror2. 
The Nizina district is located about eighty miles north of Behring 
glacier between parallels 61° 12’ and 61° 37’ north latitude and meridians 
142° 22’ and 143° west longitude, and embraces about three hundred 
square miles. The sedimentary rocks are Triassic and Jurassic with some 
Quaternary deposits and rest upon greenstone of probable Triassic age. 
Deformation and erosion followed Triassic sedimentation with exposure 
of the underlying greenstone, after which Jurassic sediments accumu- 
lated to a thickness of 7,000 feet. Younger rocks may possibly have 
been present but if so have been removed. The Jurassic rocks are 
deformed and cut by great quantities of quartz diorite porphyry in the 
form of sills and dikes. All the rocks are faulted. Most of the Quater- 
nary deposits are related to glaciation. 
Gold is the only metal at present produced on a commercial basis 
but the copper will be important when means of transporting it to the 
coast are developed. The gold is in the form of placers some of which 
are related to glacial deposits though others are not. The copper occurs 
as chalcocite and bornite with small amounts of native metal in the 
amygdaloidal form. The origin of the copper deposits is discussed briefly, 
with full recognition of the speculative nature of the chemical reactions. 
EK. Awss 
The Late Glacial and Post-glacial Uplift of the Michigan Basins. 
Earthquakes in Michigan. By WILLIAM HERBERT Hosss. 
Mich. Geol. and Biol. Surv. Pub. 5, Geol. Series 3. Pp. 87; 
DIse Aen Hes s5 ee 
This is a bulletin which is largely intended to present a phase of 
geology ina popular way. The author has preceded his discussion of the 
uplift by a series of notes and drawings of various features that are useful 
in interpreting the history of the basins. These include illustrations of 
present sinking and rising shore lines, sea cliffs, wave-built terraces, 
