[Stanza XII.] Kimmeridge clay, the lowest series of the Upper Oolitic, is dark bluish gray, shaly clay which is sometimes bituminous and occasionally, as at Kimmeridge in the Isle of Purbeck, is so rich in bituminous matter as to be used as fuel.
Beneath the cretaceous rocks in Southeast England a fresh-water formation called the Wealden is found interlaced between two marine formations. It is composed of three minor groups: Weald clay, Hastings sand and Purbeck beds, or flags of limestone and marl. The Wealden formation is rich in fossils, containing also what appear to be the oldest examples of bird fossils in Great Britain.
The Bagshot sands, or stones, consist of a series of strata of the Eocene period, overlying the London clay, the name being derived from Bagshot Heath in Surrey where they were first examined. At some places, as near Oxford, England, the Coraline crag is exposed at the surface, running to a depth of more than fifty feet. It belongs to the older Pliocene period and indicates a temperate climate.
[Stanza XIII.] The Tremadoc slate is the uppermost of the three strata comprised in the Cambrian period in Europe, covering the earliest portion of the Paleozoic or primary era.
NOTES TO “SIMILAR CASES”
[Tertiary Rocks.] It is in the rocks of this period that the fossils of the various extinct primitive quadrupeds are found.
[Eohippus.] An Eocene perissodactyl with four anterior and three posterior digits apparently allied to the Hyracotherium ancestors of horse-like animals.
[Dinoceras.] A gigantic mammal of elephantine form, having three pairs of protuberances on the upper surface of his head.
[Coryphodon.] A fossil mammal somewhat resembling the hippopotamus.
[Loxolophodon.] An extinct mammal with obliquely crested molars.