96 DONALD C. BARTON 
probable that the Passau axis of maximum is being produced by some 
such geologic feature within the crystalline basement. The center of 
gravity of the feature can be as deep as 5,000 meters, but can be 
’ shallower. 
ABSENCE OF FOLDING PARALLEL WITH ALPINE FRONT 
The determination of the presence or absence of folding parallel 
with, and in front of, the Alps was an important problem for these 
surveys. Northward thrust from the Alps against competent beds 
within the beds of the Tertiary basin should be expected to produce 
folds in front of, and parallel with, the front of the Alps. But thrust 
against a prism of wholly incompetent sediments should produce 
yielding along overthrusts but no folding ahead of the overthrusts. 
The presence of folding in front of, and parallel with, the edge of 
the Alps is not indicated or suggested by the results of the torsion- 
balance and magnetic surveys, although there is suggestion of fault- 
ing. The failure of both the magnetic and torsion-balance surveys to 
indicate or suggest the presence of such folding is not conclusive proof 
of its absence. It is conceivable that there is no vertical variation of 
magnetic permeability. Such folding, therefore, would produce no 
magnetic anomalies. The absence of any vertical variation of density 
is possible, but increase of compaction, and therefore of density, with 
depth is probable. The increase of density with depth, however, might 
be so slight that the folding would produce very faint anomalies. 
The close spacing of the torsion-balance stations was used so that 
faint anomalies might possibly be detected. The writer was unable to 
recognize any anomalies which he would interpret as indicating such 
folding. The absence of indication or suggestion of the folding by the 
results of the geophysical surveys is evidence, therefore, although not 
finally conclusive evidence, that folds of moderate or large size and 
amplitude are not present in front of the Alpine overthrusts. 
