Geology and Mineralogy. 175 
the drainage of the surrounding countries, forming two extended 
Miocene lakes. The deposits of the westernmost lake are chiefly 
the tuffs and rearranged ejecta of volcanic eruption. The deposits 
of the Plains are the simple detritus from the surrounding lands. 
The series on the west are over 4,000 feet thick; in the east they 
are not proved to be over 300 or 400 feet. Both contain abundant 
and typical Miocene vertebrate life. 
The close of the pieces was ee by a powerful oro- 
graphical movement over the area of the western Miocene lake, 
which threw the beds scotmmulated “sp its bottom into folds. Con- 
The Pliocene opened, therefore, with two enormous lakes, one 
covering y the basin country of Utah, Nevada, Idaho, and eastern 
regon; the other occupying the province of the Plains. The 
area of Miocene sediment. oth o ae Plioe cen la es — as 
the Miocene — contain the remains of rich faune. The <i ea pe 
lake received a maximum of about 2,000 i of strata; the west- 
ern lake has nowhere shown over 1 400 fee 
The close of the Pliocene was een “by another orograph- 
a movement, which threw the sediments of the Great Plains lake 
into their inclined paige ee dipping 4,000 feet to the east and 
7,000 feet to the south from the Fortieth Parallel region. This 
Instead of tilting thes eaten Re: it pekess in the middle, and the 
two sides were eae from 1,000 to 2,000 feet thick, the shores 
faulting downward. Ther esult of the post-Pliocene movement in 
the lecaxouacd of the Plaui was to give thereafter a free ee 
to the sea. The result in the area of the Great Basin was to leav 
two dee p depressi sions, ee at the western base of the Wa ahsatch, 
Se 
An a ee Geology, designed especially for the Interior 
State ‘by E. B Aa REWS on D.. : of the Obie —— Corps, 
and late | Serine in as Maries College. 283 pp. 8 Cineinnati, 
1878. (Van Antwerp, Bragg & Co.)—In this little ‘work on Ele- 
mentary Geology, the author, as his preface remarks, has had 
especial reference to the Interior portion of the United States, ex- 
clusive of the Sontharn States. Many of the illustrations and facts 
os accordingly from the formations of the Mississippi Valley. 
still a general review of the science, presenting briefly facts 
