FORMATION OF NORTHERN GERMANY. 119 
tuated the entrances to labyrinthine quarries, close to which 
numerous fossils are found. 
Several geologists have referred to this division of the chalk 
the strata which constitute the upper portion of the Louisberg 
(Lausberg) near Aix la Chapelle, and especially the stratum, 
about four feet in thickness, of yellowish sandy limestone, with 
the layer beneath it from 1 to 2 feet in depth, consisting of 
flints, hornstone and limestone. This latter is said to contain 
a large number of the Maestricht fossils; unfortunately I have 
not been able to discover even a single one. We shall enter into 
more detail on this subject in the following section. 
It has hitherto been generally admitted that the Maestricht 
formation is more recent than the upper white chalk; and this 
deposit has even been represented as a connecting member be- 
tween the chalk formation and the tertiary deposits, but I think 
without reason, and I cannot but consider it as a true equiva- 
lent to the English white chalk with flints. 
There occur, it is true, among the fossils of Maestricht and 
Falconberg, several which appear to be absent in the upper 
chalk of other districts, for instance, Astrea, Diploctenium, Orbi- 
tolites, Crassatella latissima, &c.; but hitherto we have not suc- 
ceeded in detecting even a single species which had been found 
in other places along with any tertiary species; while, as re- 
gards the characteristic forms of the upper chalk,—such as Mo- 
sosaurus Hofmanni, Callianassa Fawasti, Belemnites mucronatus, 
Apiocrinites ellipticus, and the numerous small corals,—they 
nearly all occur at Maestricht and Falconberg. Even if it 
should be proved that this formation is actually underlaid (un- 
terhaiift), above Maestricht and at Henri Chapelle, by a pure 
white chalk, the latter will doubtless prove to be the lower chalk 
(“chalk without flints” of the English). 
It will not appear surprising that some fossils should occur at 
Maestricht which are absent in other districts, if we take into 
consideration the peculiar mineralogical nature of the Maestricht 
stone, which was certainly produced by circumstances which did 
not exist contemporaneously on the English coast. But a dif- 
ference in the mineralogical properties of the rock would not 
alone justify our inferring a difference in the age of the deposit, 
even if the upper chalk marl, which we shall presently consider, 
were allowed to be an equivalent of the upper chalk itself. 
