THE GEOLOGY OF SWITZERLAND. 39 
Cretaceous. 
As in the Jurassic period, so also in the Cre- 
taceous, Switzerland was under the sea. To the 
east, however, was dry land. The complete dif- 
ference between the animals of the Malm or Upper 
Jurassic, and then of the Neocomian or Lower Cre- 
taceous, appear to imply a change of conditions or 
great lapse of time. It was at one time supposed* 
that the southern shore of the Swiss Cretaceous Sea 
followed a line drawn from the Walensee to Altorf, 
the Lake of Brienz and Bex, but though this is the 
present limit of the strata they once extended much 
farther, and have been removed by denudation. 
Heim considers that islands began to show them- 
selves in the region of the Central Alps in Cretaceous 
times. 
The Swiss Cretaceous strata fall into five principal 
divisions. The first or oldest — ' Valangian — consists 
of a dark hard silicious and sometimes oolitic lime- 
stone as on the Sentis, or of bluish grey marls and 
limestone as in the Jura. 
The Neocomian, from the old name of Neu- 
chatel, is sometimes a dark gray or black hard marl, 
sometimes a bluish grey marl which easily disinte- 
Heer, Primceval World of Switzerland . 
