SURVEY OF MUNICH TERTIARY BASIN 89 
North of Regensburg, the broad faulted syncline seems to have 
been formed by the down-warping of Mesozoic formations in reference 
to the area west and by down-faulting of those formations in reference 
to the Bohemian crystalline massif. The syncline, therefore, may not 
affect the surface of the crystalline basement to the same extent that 
it affects the Mesozoic formations or may not affect it at all. The 
results of the B. M. I. magnetic survey would seem to indicate that 
within the area of the Munich Tertiary basin, the Regensburg syn- 
cline does not appreciably affect the crystalline basement. 
The question is open whether within the Munich Tertiary basin: 
(1) the Landshut ridge is the effect of positive arching along a Land- 
shut structural axis; or (2) the effect of the negative down-warping 
of the Regensburg syncline. The isogams of the torsion-balance sur- 
vey agree qualitatively with Schiitte’s isogams of the Bouguer anom- 
alies. In the extreme eastern part of the basin, the isogams tend to bend 
into parallelism with the front of the Bohemian massif. In that area, 
the west-southwestward dip of the surface of the crystalline complex 
under the sedimentary formations may be producing an appreciable 
effect on the variation of gravity at the surface. It is possible also that 
the Mesozoic basement under the Tertiary formation may rise east- 
northeastward up toward the Bohemian massif. North of Regensburg, 
the syncline seems to have been produced by negative movement in 
front of the Regensburg fault. Similar structural movement south of 
Regensburg, within the Tertiary basin, would produce a Landshut 
ridge and a continuation of the Regensburg syncline, which in turn 
would produce the observed variation of gravity. The Landshut ridge, 
however, would not represent the effect of a positive axis of deforma- 
tion. 
BASALTIC STRUCTURES ALONG DANUBE 
A line of previously unsurmised structures with basaltic cores was 
mapped along Danube River from Vohburg to Ulm. The Ingolstadt 
structure is one of the most pronounced of those structures and is the 
only one which is crossed by both the magnetic and the torsion-bal- 
ance surveys. It has a sharp gravity maximum and a sharper mag- 
netic maximum. The magnetic isogams are shown in Figure 8. The 
north-south profiles of relative gravity (Ag.), of the horizontal gra- 
dient of gravity (U..), and of relative Z, are.shown in Figure 9. The 
amplitude of most of the residual anomalies within the area of the 
survey is +25 gammas from the regional value of Z, of Figure 4, al- 
though a few residual anomalies have an amplitude of +50 or —50 
gammas. The residual maximum of the Ingolstadt structure has an 
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