Review of Recent Geological Literature. 355 
0. The Vermilion series of mica schists and hornblende schists, 
more fully and generally crystalline than the preceding, but of similar 
origin. 
7. Laurentian gneiss, often conformable with the Vermilion schists, 
from which it then is distinguished by a gradual downward increase of 
feldspathic and silicious ingredients. More frequently, however, these 
lower members of the Archaean complex are divided by a zone of disturb- 
ance, upheaval, and brecciation, with dikes and laccolite masses of 
the granitic Laurentian extending upward into the Vermilion series, or 
where this is wanting, into the less crystalline Keewatin schists. Evi- 
dently some of the Laurentian rocks were fluid or plastic after or during 
the time when the overlying Vermilion and Keewatin members of the 
Archaean complex attained nearly their present lithologic condition. 
The Mesabi Iron Range. By Horace V. Wincheli., pp. 111-180, with 
6 plates and 9 figures in the text. (Twentieth Annual Report, Geol- 
Survey of Minnesota.) The latest discovered and probably the richest 
of the numerous iron-producing belts in the region of lake Superior is 
the Mesabi iron range, in northeastern Minnesota, lying 15 to 20 miles 
south of the Vermilion iron range, where extensive mines of hard hem- 
atite have been very successfully worked during the past ten years. 
The chief ore of the Mesabi mines is soft hematite, easily excavated 
with only the pick and shovel and capable of being rapidly worked with 
a steam shovel, lying in nearly flat deposits which have a variable thick- 
ness up to 100 feet, being usually overlain only by 10 to 50 feet of glacial 
drift. Its earliest discovery in sufficient deposits for profitable mining 
was in November, 1S90, at the Mountain Iron mine, and the next at the 
Biwabik mine in August, 1891. Since that time about twenty other 
merchantable deposits of this ore have been found. and nearly a hundred 
miles of railroads have been built for its transportation to Duluth, to be 
shipped thence to Cleveland, where coal is cheaply furnished for smelting 
furnaces. Contracts have been made by the companies now developing 
these mines for the yearly shipment of 1,500,000 tons of ore, equal to 
about a sixth of the present lake Superior product. The cost of mining 
and loading the ore on cars is estimated to average 25 cents per ton, and 
of its delivery in Cleveland about $3, leaving a profit of a dollar per ton at 
the present Cleveland prices for ores of the Bessemer grade here mined. 
The stratigraphic relationship and conditions of origin of the Mesabi 
iron ores are well described and discussed by Mr.Winchell,who attributes 
the original deposition of the interbanded jasper and hematite beds to 
oceanic sedimentation, both chemical and mechanical, but the present 
concentration of the ores as soft hematite deposits of great thickness 
and purity is referred to the action of infiltrating water while this area 
has been a land surface undergoing slow subacrial erosion. Silicious 
portions of the iron-bearing strata have been dissolved and replaced by 
the ore, which preserves the bedding planes, joints, and even differences 
in texture, of the original layers of jasper, chert, taconyte, and slate. 
The underlying portion of the Pewabic quartyzte appears to have 
received the greater part of the removed silica, becoming an impervious 
floor beneath the ore deposits. The beds usually dip 10'=' to 20° S.or S.E., 
