Reviezu of Recent Geological Literature. 121 
neath, with nearly vertical bedding and lamination, moved up by fault- 
ing and slipping, frequently on planes of schistosity: Erosion has 
left laccoliths covered, partially uncovered, and deeply dissected, and in 
places has removed them entirely or left only scattered remnants. Con- 
duit, basement contact, wedge, flank, crest — all parts of the laccolith 
are exposed, in plan and section in different places in the Black Hills. 
The evidence quoted points to Eocene time as the age of intrusion. There 
were several thousand feet of strata above the laccohths, and the soft 
Cretaceous shales absorbed laterally the doming produced by individ- 
ual intrusive masses Intrusion is not conceived to have been in 
any sense a cause of the greater uplift, but an effect. The intrusions 
were a small incident in a great movement of elevation. The greater 
uplift probably took place after the close of the Laramie, along with 
similar movements in the Big Horn Range and the Rocky ]\Iountains. 
Whatever their cause these movements were colossal and involved a 
considerable section of the earth's crust. ...... .The fractures reached 
downward to a zone where molten rock was under pressure. The 
liquid shot upward into every ramification of the fracture system." 
In the last chapter of this paper, Ernest Howe describes a series of 
very instructive laboratory experiments illustrating intrusion and ero- 
sion, "imitating as far as possible the processes involved in the form- 
ation of laccoliths and the resulting deformation of the invaded beds." 
Prof. C. R- Van Hise, in the third paper, treats of "The iron Ore 
Deposits of the Lake Superior Region," noticed in editorial comment 
by U. S. Grant in the last January Ajieric.\n Geologist. Among the 
maps illustrating this paper are three of large size, folded, on the scale 
of a mile to an inch, showing the geology and contour of parts of the 
Menominee, Vermilion and IMesabi iron-mining districts. 
The next two papers, by Charles Willard Hayes, describe "The 
Arkansas Bauxite Deposits," and "Tennessee White Phosphate." Baux- 
ite, recently in great demand for the production of aluminum, has been 
known to occur abundantly in Arkansas since its deposits there were 
first described in 1891 by Dr. J. C. Branner, the state geologist. Owing 
to the approaching exhaustion of its only other important deposits known 
in the United States, in a district of Georgia and Alabama, extensive 
mining of the bauxite in Arkansas will brobably begin soon. It is 
estimated that about six million tons are in view in outcrops, and that 
deep mining will supply more than forty million tons- "About 2 tons 
of bauxite are required for the production of i ton of alumina. The 
value of the bauxite at the mine is about .S3 per ton, whereas the value 
of the alumina is $60 per ton." 
The white phosphate deposits of Perry county, Tennessee, as shown 
by Mr. Hayes, were formed in caverns of Silurian limestone strata, 
being thus essentially pockets, though occasionally of large extent. Tlie 
amount in any locality can be estimated only after a systematic exploit- 
ation. Some of these deposits are now being actively developed by 
mining. 
Dr. George F. Becker presents the final paper of this volume, a "Re- 
port of the geology of the Philippine Islands," of which an advance 
