770 LTC. CHAMBLEE, 
sheets of glacial débris. The latest drift sheets show this best. 
That designated Wisconsin is accentuated by nearly a score of 
peripheral ridges. Ina recent admirable paper by Keilhack* it 
is shown that similar lines of halt, and perhaps of minor advance, 
mark the corresponding European glacial sheet as ‘deployed on 
the plains of north Germany ; indeed, even in some of the greater 
details, a striking correspondence is traceable between the two 
series, whose general identity in age and kind were long since 
noted by Salisbury. These minor oscillatory phenomena seem, 
therefore, sufficiently general and sufficiently important to require 
an explanation, and this explanation is not necessarily connected 
with the fundamental cause of glaciation. The preceding dis- 
cussion carries in itself a suggestion which is worthy of note in 
passing. If the localization of the great ice-sheets was depend- 
ent on the general circulation of the atmosphere, any periodic 
shifting of the circulation of moderate magnitude might be com- 
petent to cause a shifting of the ice-sheets of corresponding 
nature. There are historical facts that give some color to the 
notion that such shiftings have taken place within the period of 
human records. The oscillations of existing glaciers point in a 
similar direction. There is clearly a secular shifting of terres- 
trial magnetism, but the nature of its cycle is yet undetermined. 
Current opinion gives it a periodicity which would quite well 
satisfy the demands of the concentric moraines. 
GLACIATION NEAR THE CLOSE OF THE PALEOZOIC ERA 
While the occurrence of extensive glaciation in India, Aus- 
tralia and South Africa near the close of the Paleozoic era may 
be regarded as fully established, a specific discussion of its 
origin along the lines of an atmospheric hypothesis presents for- 
midable difficulties, because the exact date of the glaciation, its 
tDie Stillstandslagen des letzten Inlandeises und die hydrographische Entwick- 
elung des pommerschen Kiistengebietes. Separatabdruck aus dem Jahrbuch der 
konigl. preuss. geologischen Landesanstalt fiir 1898. Berlin. 
Terminal Moraines in North Germany. Am. Jour. Sci., Vol. XXXV, p. 401. 
Series 3. 
