UPPER MIOCENE OF SWITZERLAND. 
219 
occur, with innumerable insects in a wonderful state of pres¬ 
ervation, usually found singly. Below this is an indigo-blue 
marl, like that at the bottom of the higher quarry, resting on 
yellow marl ascertained to be at least thirty feet thick. 
All the above fossil-bearing strata were evidently formed 
with extreme slowness. Although the fossiliferous beds are, 
in the aggregate, not more than a few yards in thickness, and 
have only been examined in the small area comprised in the 
two quarries just alluded to, they give us an insight into the 
state of animal and vegetable life in part of the tipper Mio¬ 
cene period, such as no other region in the world has else¬ 
where supplied. In the year 1859, Prof. Heer had already 
determined no less than 475 species of plants and more than 
800 insects from these (Eningen beds. He supposes that a 
river entering a lake floated into it some of the leaves and 
land insects, together with the carcasses of quadrupeds, 
among others a great Mastodon. Occasionally, during tem¬ 
pests, twigs and even boughs of trees with their leaves were 
torn off and carried for some distance so as to reach the lake. 
Springs, containing carbonate of lime, seem at some points to 
have supplied calcareous matter in solution, giving origin lo¬ 
cally to a kind of travertin, in which organic bodies sinking 
to the bottom became hermetically sealed up. The laminae, 
says Heer, which immediately succeed each other were not 
all formed at the same season, for it can be shown that, when 
some of them originated, certain plants were in flower, where¬ 
as, when the next of these layers was produced, the same 
plants had ripened their fruit. This infer¬ 
ence is confirmed by independent proofs de¬ 
rived from insects. The principal insect-bed 
is rarely two inches thick, and is composed, 
says Heer, of about 250 leaf-like laminae, some 
of which were deposited in the spring, when 
the Cinnamomiim polymorphum (Fig. 138) 
was in flower, others in 
summer, when winged 
ants were numerous, 
and when the poplar 
and willow had ma¬ 
tured their seed; oth¬ 
ers, again, in autumn, 
when the same Ginna- 
momum poly m orphum 
(Fig. 138) was in fruit, 
as well as the liquid- 
ambar, oak, clematis, 
FI<?. 
Cinnamomum polymorphum. Ad. Brong. 
and Lower Miocene. 
Upper 
a. Leaf. 6. Flower, nat. size ; Heer, PI. 93, Fig. 28. 
c. Pipe fruit of Cinnamomum polymorphum, from 
(Eningen; Heer, PI. 94, Fig. 14. d. Fruit of recent 
Cinnamomum camphoriim of Japan ; Heer, PI. 
152, Fig. 18. 
