AvuGusT 18, 1899.] 
and London, Ky., respectively. The last 
two, the Richmond and London, include 
the western margin of the field. The east- 
ern margin is described in several of the 
folios published, and others are in course of 
preparation. 
Studies in Pleistocene geology have been 
pursued by Professor Chamberlin and his 
assistants during more than a decade. 
Through a conservatism which justifies 
confidence, even though the impatient may 
at times have thought it excessive, the pub- 
lication of results has been postponed until 
the criteria for discriminating the several 
episodes of glacial occupation and the vari- 
ous genetic types of glacial formations have 
been fully elaborated. The final prepara- 
tion of manuscript was, however, begun 
nearly two years ago, and the first of a 
series of monographs upon the Pleistocene 
history (Monograph XX XVIII., The Illi- 
nois Glacial Lobe, by Frank Leverett) is 
issued. In this connection also may be 
mentioned Monograph XX XIV., The Gla- 
cial Gravels of Maine and their associated 
Deposits, by Geo. H. Stone. 
The extraordinarily difficult investiga- 
tion of the relations of iron-ore deposits in 
the Lake Superior region, which was begun 
by Irving and has been continued under 
Van Hise, is approaching a successful com- 
pletion. All of the great iron-producing 
districts except two have been carefully 
surveyed, and the field work on these, the 
Vermilion and Mesabe districts of northern 
Minnesota, is far advanced. The series of 
monographs which set forth the observa- 
tions and conclusions are a monument to 
the scientific spirit and executive ability of 
their authors. It is probably not too much 
to claim for them a foremost place in the 
rank of great geologic works. Very rarely 
has a problem of equal magnitude and diffi- 
culty been so elaborately studied and ade- 
quately solved. The principles of investi- 
gation developed in the course of this work 
SOIENCE. 
207 
are a contribution to geologic methods and 
will facilitate further researches of a similar 
character. To name only the Jlatest of 
the resulting publications, reference may 
be made to Monographs XXVIII. and 
XXXVI., the former entitled ‘The Mar- 
quette Iron-bearing District of Michigan,’ 
by C. R. Van Hise and W.S. Bayley, and 
the latter, ‘The Crystal Falls Iron-bearing 
District of Michigan,’ by J. M. Clements 
and H. L. Smythe, published also in con- 
densed form in the 19th Annual. 
Studies of the stratigraphy of the Great 
Plains, more especially of the content of 
artesian waters, form an important item in 
the list of activities of the Survey. In the 
Pueblo folio the standard was set for pre- 
cise discrimination of the formations and 
adequate illustration of their distribution 
and structure. The Geologic Branch, 
cooperating with the Hydrographic Branch, 
has extended more general investigations 
over parts of Nebraska and South Dakota. 
At present the surveys are being executed 
for the eastern and south margin of the 
Black Hills and the adjacent plains. 
The latest contribution to the subject isa 
preliminary report on the geology and 
water resources of Nebraska by N. H. 
Darton in the 19th Annual Report. The 
18th Annual also contained an article on 
‘New Developments in Well Boring and 
Trrigation in Southeastern South Dakota.’ 
Observations of the temperatures of artesian 
waters have led to the discovery of inter- 
esting variations in underground tempera- 
tures which are being made the subject of 
careful investigation. 
In the southern portion of the Great 
Plains province work is progressing in In- 
dian Territory. The coal fields of Indian 
Territory are structurally related to a series 
of folded and faulted sandstones and lime- 
stones along their southern margin, as the 
Cumberland plateau is related to the forma- 
tions of the Appalachian Valley. The coals 
