DEC. 4, 1923 PROCEEDINGS: WASHINGTON ACADEMY OF SCIENCES 447 
in effect, the altitude of all lands in high latitudes. It would also exert a 
powerful force tending to cause high-standing crustal masses in high and 
middle latitudes to creep away toward low latitudes, leaving rifts near the 
poles, and causing folding, faulting, and uplifting, with narrow outside fore- 
deeps in a marginal belt toward the equator, precisely as is so well ex- 
emplified in the distribution and characteristics of the great Tertiary moun- 
tain belt. To accomplish this, the Earth, in the writer’s opinion, must be 
supposed to have a solid, rigid central body, viscous to prolonged stress in 
a film next beneath the zone of fracture. 
The crustal movements and mountain-making of the earlier geologic 
periods are not related in any way to the Moon’s tidal force, for the Moon 
had not then been captured. - They are, in all probability, related to the 
solar tidal force which was much more powerful in its action on the Earth, 
when the Earth was nearer to the Sun. (Author’s abstract.) 
A critical review of the Taylor-Wegener hypothesis was next presented by 
Prof. Regrnatp A. Daty, Harvard University. 
According to Pepper’s Playbook of metals, published in 1861, the sug- 
gestion that continents have migrated through long distances had already 
been clearly expressed by M. A. Snider. The idea was adopted by O. Fisher 
in his Physics of the Earth’s crust (1889), and has been greatly elaborated 
by F. B. Taylor (1910) and A. Wegener (1912-1922). The general grounds 
for the hypothesis include: many topographic, structural, and _ biological 
(paleontological) correspondences among the continents; the difficulties of 
land-bridge theory; the difficulties facing other theories of crustal deforma- 
tion; and the asymmetry, arcuate plans, of mountain chains. The follow- 
ing abstract relates especially to Wegener’s statement. 
Wegener assumes (1) that essentially all of the Paleozoic land formed one 
continent, which had been derived from a universal salic shell of the primi- 
tive earth; (2) the flotation of this unique continent in a practically fluid, 
basaltic shell (the Sima), which also floors the whole ocean; (3) the existence 
of a force sufficient to cause a drift of continental blocks toward the equator 
(the Polflucht); (4) the existence of a force sufficient to move each continent 
to the westward (Westwanderung); and (5) the spasmodic displacement of 
the earth’s axis of rotation with reference to the crust, and that through 
many tens of degrees. 
He concludes that the Polflucht force caused the east-west mountain chains 
of the Paleozoic, Mesozoic, and Cenozoic eras. During the Mesozoic the 
great continent was broken into large fragments which then, and at inter- 
vals until the present day, drifted, and either separated, with the formation 
of the Arctic, Atlantic, and Indian oceans, or collided, with the development 
of mountain ranges in the loci of collision. He explains all islands as funda- 
mentally salic, representing the smaller fragments; the arcuate mountain 
ranges of eastern Asia are fragments left behind during the westward migra- 
tion of Eurasia. With these exceptions all mountain chains are attributed 
to the downstream pressures exerted by moving continental blocks. Taylor 
had adopted the same conclusion but made no exception of the east-Asiatic 
arcs, whose asymmetrical but systematic plan prompted his statement of 
1910. 
Wegener’s assumption of practically no strength in the sub-oceanic crust, 
the salic, continental part having notable strength, is basal to his whole 
reasoning and yet appears to be quite indefensible. Believing the Szma, 
cold or hot, to be essentially fluid, he could permit himself to think that 
