56 SECTIONAL ADDRESSES. 
Many eminent geologists bowed to authority and accepted that restriction. 
Huxley, with his usual insight, repudiated it as incredible and as due to the 
mathematical reasoning being based on an unsound foundation. Huxley’s 
faith in geological observation has been fully justified and should encourage 
geology to apply the same test to isostacy. 
The mathematical data for the permanence of the ocean basins seem 
unreliable. The claim that the ocean floors consist of a continuous sheet 
of heavy material (sima) was supported by gravity determinations; but 
the calculations are based on the assumption that the sea surface stands 
at the spheroid of reference ; they disregard all variations in sea-level due 
to differences in specific gravity, to the piling up of the water by wind 
and by the lateral attraction of the land. The observations by Duffield 
during the voyage to Australia of the Association in 1914 did not fully 
confirm Hecker’s results; and the work of Meinesz is inconsistent with 
the views that the ocean bed is a sheet of basic rock, and that its level is 
determined simply by its specific gravity. 
A stronger argument was based on the claim that earthquake waves 
travel more quickly under the oceans than under the continents ; but the 
waves from the earthquake off the Newfoundland Banks on November 18, 
1929, went westward under North America to California at the same 
pace as under the Atlantic, even below two of its deeper basins, to Spain. 
That some parts of the crust are in such delicate isostatic equilibrium 
that the surface rises when material is removed by denudation and sinks 
when loaded with more sediment is well established; but other parts 
of the surface have riot this delicate poise. Regions are worn down to 
low-lying peneplanes, without being automatically uplifted. Basins may 
be filled by sediment without the subsidence of the floor which may indeed 
be uplifted while it is receiving an additional load. Thus parts of 
Palestine appear to have stood above sea-level from pre-Cambrian to 
Middle Cretaceous times; the country then sank below an open sea: 
sediments were laid down upon its floor, and show gradual shallowing 
conditions, due to the sea having been displaced either by the material 
or by the uplift of the floor. After the Cretaceous Era the land emerged 
from the sea and subsequently the floor of the Jordan rift-valley subsided 
until the shore of the Dead Sea was 1,300 feet below sea-level. This 
subsidence was not due to a load of sediment, as only a thin sheet had 
been deposited over the sunken floor. Moreover, in parts of the world 
faults have a downthrow of 10,000 feet, and there is no evidence that 
their cause was sedimentation. The dependence of subsidence and 
sedimentation may be often true for the geosynclines which, owing to the 
rupture or instability of the crust in consequence of its deformation, are 
bands of long-continued weakness—or asthenostrophes (weak bands or 
belts). 
tied to accept the hydrostatic equilibrium of all parts of the 
crust is not due to prejudice against isostacy. I supported that doctrine 
when those who thought that the removal of a few feet of rock could 
affect the level of the crust were chided for credulity, although the rise 
and fall of the shore in places with the ebb and flow of the tide already 
rested on accurate observation. That effect has since been fully established. 
But the extension of isostacy to the whole surface of the earth and the 
