326 The American Geologist. May, 1805 
from this a more or less distinct transition can be traced to 
the last of the series in the Pleistocene or perhaps even the 
post-Pleistocene (Human) period. 
The remains were found in a bed of blue clay about seven 
feet thick and extended from bottom to top, and even in one 
case protruded below into a gravel and above into a yellow clay. 
The age of this still remains in doubt. A few recent fresh 
water shells of small size were found in sand-pockets in the 
clay, but their evidence is not sutficient to decide the question. 
Dr. Edward Orton is "of the opinion that the mastodon re- 
mains are of post-Glacial age," and possibly, in the absence 
of conclusive testimony, this is the safest position. But from 
the paleontological side comes a strong suggestion of greater 
antiquity which further evidence may confirm. k. w. c. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
The Penokee Iron-bearing series of Michigan and Wisconsin. B3' Roland 
DuER Irving and Charles Richard Van Hise. (Monograph xix, U. S. 
Geol. Survey, Washington, 1892. Publislied 1894.) This long-advor- 
tised volume appeared from the Government printing office in the latter 
half of 1894. The death of Prof. Irving in May, 1888, deranged the 
plans and tlie worl^c and devolved the chief responsibility u\)o\\ Prof. 
Van Hise. The latter was formerly a student of Irving, and well un- 
derstood Irving's purposes as well as his geological ideas, and he has 
mirrored them faithfully, there being but slight departure from the 
well-known views which Irving entertained on the geolegy of the Peno- 
kee series. For instance, in the matter of the ta.xonomy and the geo- 
graphical distribution of the formations of the Lake Superior region as 
e.xhibited in plate i of this work, they are the same as exhibited in plate 
XXII of the Fifth annual report of the U. S. Geol. Survey (1883-84) pre- 
pared by Irving eleven years earlier to accompany his "Preliminary 
paper on the investigation of the Archean formations." Tlierc is a 
slight change in the extension of the Mesabi iron range to the Missis- 
sippi river, and in the spur of the iron-bearing series which runs north- 
westward from Marquette, and the term Algonkian is fully introduced. 
Irving proposed Eparchean or Agnotozoic, but the vote of the geologists 
of the survey determined in favor of the term Algonkian. On this r-late, 
therefore, everything that was before called Huronian by any one is 
still called Huronian, but this term and these areas are united with Ke- 
weenawan and Keweenawan areas under the single designation Algon- 
