152 
various depths and also a specimen from the 
surface of the prospect. The samples did not 
contain any of the salt except the one taken 
from the very surface. On this the nitrate was 
a coating about a quarter.ofan inch in thickness, 
and, as the previous sample sent, was approxi- 
mately pure potassium nitrate. So far, the 
salt found is in very limited quantities and there 
are no explanations to offer for its existence or 
accumulation. It is evident that it has been 
brought in and deposited upon the sandstone 
but the source has not been detected. Owing 
to the winter months being close at hand when 
the discovery was made, it was not possible to 
carry on any extended examination. Potassium 
nitrate has been found in very minute quanti- 
ties in the Leucite hills by Cross ; this, however, 
is the most important discovery ever made in 
the State, and may result in the location of 
nitrate deposits of commercial importance. 
WILBuR C. KNIGHT. 
GEOLOGICAL LABORATORY, 
UNIVERSITY OF WYOMING, 
Jan. 16, 1901. 
CURRENT NOTES ON PHYSIOGRAPHY. 
SOUTHERN WISCONSIN. 
“THE Geography of the Region about Devil’s 
Lake and the Dalles of the Wisconsin’ by R. 
D. Salisbury and W. W. Atwood (Wis. Geol. 
and Nat. Hist. Survey, Bull. v, Educational 
series, 1, Madison, 1900), is a significant publi- 
cation if for no other reason than that it is 
concerned with geographical features and that 
it is a State publication ‘primarily designed 
for use in the schools.’ State surveys have 
been very slow in coming to recognize their 
responsibility in this direction; and we are 
glad to see Wisconsin now following Missouri, 
New Jersey and Maryland. The region de- 
scribed includes a typical resurrected mountain, 
Baraboo ridge, of Huronian quartzite, adjoined 
by a plain of erosion, too smooth over much of 
its extent to be called a peneplain, formed by 
the removal of paleozoic strata which once 
buried the ridge, and which still remain in 
isolated castle-like hills here and there over 
the plain, and more continuously in hilly up- 
lands farther southwest. The Dalles of the 
Wisconsin river are cut in the plain where the 
SCIENCE. 
_[N.S. Von XII. No. 317. 
river has been displaced by glacial action from 
its former course. The 150 pages of the report 
are illustrated by 38 plates and 47 figures, and 
closed with a good index. 
THE ISLANDS OF SOUTHERN CALIFORNIA. 
“A TopoGRAPHIc Study of the Islands of 
Southern California,’ by W.S. Tangier Smith 
(Bull. Dept. Geol., Univ. Cala., ii, 1900, 179- 
230) presents additional details concerning the 
features of this interesting group. The author 
points out that on a single shore line a wave- 
cut terrace of much strength may be developed 
where the coast has a moderate resistance and 
gentle slope, while hardly any shore marking is 
made where the coast is more resistant and of 
steeper slope. On San Clemente the rocks are 
relatively resistant and the general slope of the 
island is moderate; here wave-cut terraces at 
various levels have been remarkably developed 
and wonderfully preserved. 
The occurrence of such terraces suggests 
some observations regarding the origin of those 
plains, of erosion which now stand somewhat 
above sea level and are moderately dissected by 
streams, as in the Piedmont district of eastern 
Virginia and in the peninsula of Brittany. On 
both these plains the broad uplands are sheeted 
over with heavy soils of local weathering ; the 
valleys that dissect the uplands are narrow and 
steep-sided. If the plains were of subaérial 
origin the abundant soils would be an appro- 
priate feature; if the plains were the result of 
marine abrasion, the soils must have been 
developed by weathering on the wave-cut rock — 
floor in the same period of time as that required 
for the erosion of the narrow valleys. The 
terraces of San Clemente may perhaps afford 
means of comparing the rate of soil production 
and valley erosion, and thus of giving further 
evidence regarding the origin of the districts in 
question. 
DEECKE’S ITALIEN. 
A worRK on the general geography of a 
country should not be criticised too closely 
with regard to its physiographic chapters, for 
there are many other lines toward which the 
chiefinterest of the author may have been drawn 
more strongly. It is nevertheless instructive 
to examine the method of treating land forms 
