FORMATION OF NORTHERN GERMANY. 147 
formation originated at the time when the ocean deposited the 
Neocomian ; since however the Hils-clay on the Deister, and the 
Hils-conglomerate at Osterwald, are most decidedly superior to 
the Weald-clay, that contemporaneity of origin is conceivable only 
with respect to the true Spatangus-limestone ; and this appears 
to be entirely absent in England and in North Germany, where 
on the other hand the Weald-clay formation is pre-eminently de- 
veloped. It will perhaps be possible to determine the true rela- 
tion of the Neocomian to the Weald-clay in the Alps. 
GENERAL STRATIGRAPHICAL RELATIONS OF THE SEVERAL 
GROUPS ABOVE MENTIONED. 
Having considered the separate portions of the north German 
chalk formation, and endeavoured to establish their palzonto- 
logical characters, we have still to give an idea in a few lines of 
their general stratigraphical relations. 
The first point here deserving of observation is, that the chalk 
formation is found only on the southern borders of and within 
the low region in North Germany, which is covered with sand, 
and cannot be traced southwards even so far as the oolitic for- 
mation. This is evident, for instance, in the valley of the Leine, 
where the lias reaches to Geettingen, but the chalk only to the 
neighbourhood of Vincentburg near Alfeld. If, moreover, we 
bear in mind that no further trace of the chalk formation can be 
detected in the whole district between the Wirtemberg and the 
French Jura, it is evident that, after the deposition of the oolitic 
mountains, considerable upheavings must have added very much 
to the land, but have encroached upon the ocean at that period. 
That similar upheavings were likewise continued or repeated, 
during and after the deposition of the chalk formation, is self- 
evident, since its strata, when they are not perfectly horizontal, 
frequently exhibit a considerable inclination, and are even some- 
times thrown backwards with a reversed dip. In the western por- 
tion of our district, at Aix-la-Chapelle, we find only the upper, at 
Vaéls, only the lower chalk marl; they rest almost horizontally 
upon the older coal formation, and do not appear to have been 
subjected to any upheaving subsequent to their deposition. 
In Westphalia we find several separate ranges of hills belong- 
ing to the chalk formation; thus the plener (gray chalk-marl) at 
| Ahaus,—the upper chalk-marl at Dulmen,—the lower at Coes- 
| ae 
