100 
ROLLIN D. SALISBURY 
the Geology of Crowley’s Ridge in Arkansas, the investigations 
on the Glacial formations for the Federal Survey, the work on the 
old drift and fluvial deposits of New Jersey, for the geological 
survey of that state, and his various activities in connection with 
the Geological Survey of Illinois. 
The joint memoir on the Driftless Area is, perhaps, his most 
pretentious effort along the lines of research. During the pro¬ 
gress of the investigation it fell to him to make over 1800 meas¬ 
urements of the soil mantle, and the microscopic examinations of 
the silts. The problem is tersely stated in the introductory: “In 
the midst of the great mantle of drift that overspreads the Upper 
Mississippi Basin there lies a drift barren tract of about 10,000 
square miles, the driftless area of Wisconsin and the adjoining 
States. This island in the sea of drift is unique. To find that the 
crest of an eminence towered above the great mer de glace would 
not be remarkable; to find that the summit of a plateau near the 
border of the drift-covered area lifted itself above the invading 
ice would create no surprise; but to find a broad tract lying in the 
very valley of the great river of the region, overlooked by higher 
land on different sides, and yet untouched by the glaciation that 
prevailed all around, very naturally awakens marvel. Strangely 
enough, the margin of the drift on almost every hand lies in a 
slope descending towards the driftless district. The drift-bearing 
ice was stayed in its course, not by some acclivity, not by some 
great topographic barrier it could not overcome, but by some 
agency that arrested it in its downward career on the slopes to¬ 
wards the unglaciated basin.” At the end the entire discussion 
is adroitly condensed into a single sentence: “Diverted by high¬ 
lands, led away by valleys, consumed by wastage where weak, 
self-perpetuated where strong, the fingers of the mer de glace 
closed around the ancient Jar din of the Upper Mississippi Valley, 
but failed to close upon it.” 
The Glacial studies in Greenland were undertaken by Professor 
Salisbury when he was a member of the Peary Relief Expedition 
of 1895; and the chief results appeared in a series of finely illus¬ 
trated articles which ran through the Journal of Geology during 
the years of 1895 and 1896. The introductory paper was modest¬ 
ly entitled “The Greenland Expedition of 1895.” His own sum¬ 
mary statement concerning the observations made is briefly but 
