OcTOBER 6, 1899. ] 
the geologist will have disappeared. At 
the mammoth hot springs the activity is not 
one-tenth that of former times, Minerva 
Terrace having become extinct (since 1895); 
the discharge from Pulpit and Jupiter Ter- 
races having greatly declined during the 
same period and the Narrow Gauge—a fis- 
sure vent—and other attractions, having 
become all but extinct. Roaring Mountain 
is now silent though steaming. In the 
Norris Geyser Basin the Black Growler is 
less active. In the Lower Basin the splendid 
Fountain Geyser is extinct, with a feeble 
substitute near by, called the Dewey. The 
Giant Paint Pots are greatly contracted in 
size—the pink half being extinct. In the 
Upper Basin some of the better known as 
well as many of the lesser geysers are ex- 
tinct or supposed to be. Among these are 
the Splendid Geyser and the Beehive Gey- 
ser. The Grand Geyser, which used to 
erupt daily, now erupts irregularly about 
three times a season. The Cascade, which 
erupted about every quarter of an hour in 
1895 now erupts once a day. 
The general impression of frequenters of 
the Park is that the changes are serious and 
much more rapid than is generally believed. 
‘Greatest Area and Thickness of the 
North American Ice Sheet,’ Warren Up- 
ham, St. Paul, Minn. 
From the overlapping and intermingling 
of the drift deposits the indications are that 
the ice sheet at its culmination reached 
continuously across the continent from New 
England to British Columbia or southeast- 
ern Alaska, interrupted only in its southern 
part by the projecting ranges of the Rocky 
Mountains. The conclusions of Dr. G. M. 
Dawson that the Cordilleran glaciation 
mainly preceded the glaciation of the Laur- 
entine region and of the great plains stretch- 
ing westward nearly to the Rocky Moun- 
tains, and that the maximum extension of 
the Laurentide ice sheet was attended by a 
depression of the Cordilleran region, with a 
SCIENCE. 
49} 
subsequent elevation of about 5,300 feet, is 
not apparently borne out by the facts. 
The probabilities seem to be that the Cor- 
dilleran and Laurentide ice sheets, having 
been each accumulated because of high con- 
tinental altitude much exceeding that of 
the present time, were confluent along the 
east side of the Rocky Mountains, a continu- 
ous ice sheet at the north extending from 
the east to the west side of the continent. 
In Minnesota and North Dakota observa- 
tions on each side of the Glacial Lake 
Agassiz oppose the view of Tyrrell that the 
Laurentide ice sheet was preceded by a 
Keewatin ice sheet. Facts in connection 
with glacial lake deltas and overlapping 
drift deposits demonstrate contemporaneous 
glaciation meeting from the northwest and 
northeast. There is also evidence that the 
northwestern ice field, belonging to the 
Keewatin of Tyrrell, pushed back the north- 
eastern ice field, referable to the Lauren- 
tide, showing that there the greatest exten- 
sion of the Keewatin was later. From the 
northwest and northeast, however, the two 
ice fields were confluent. This great ice 
sheet northward, as evidenced by the height. 
of mountain glaciation, attained a maxi- 
mum thickness of one to two miles nearly 
across the continent, the thickness being 
greatest upon the Laurentide highlands. 
ArTHUR HOLL LIcK, 
CoLUMBIA UNIVERSITY. Secretary. 
SCIENTIFIC BOOKS. 
Catalogus Mammalium tam viventium quam fos- 
silium. By Dr. E. L. TRovgEssart. Berlin, 
R. Friedlander & Sohn. New ed., fasciculus 
VI., Appendix and Index, 1899, 8° pp. 1265— 
1469. Price of complete work 66 Marks. 
The completion of the great ‘Catalogus 
Mammalium’ which Dr. Trouessart has been 
publishing in parts during the past two years 
marks an epoch in systematic work in mam- 
mals. Previous catalogues, incomplete at best, 
have been restricted either to living or extinct 
forms, so that zoologists have been obliged to 
