division, the
Kellaways Clay, which often contains much selenite but is poor in
fossils. The lithological characters are impersistent, and the sandy
phase encroaches sometimes more, sometimes less, upon the true Oxford
Clay. The rocks may be traced from Wiltshire into Bedfordshire,
Lincolnshire and Yorkshire, where they are well exposed in the cliffs at
Scarborough and Gristhorpe, at Hackness (90 ft.), Newtondale (80 ft.)
and Kepwick (100 ft.). In Yorkshire, however, the Callovian rocks lie
upon a somewhat higher palaeontological horizon than in Wiltshire. In
England, _Kepplerites calloviensis_ is taken as the zone fossil; other
common forms are _Cosmoceras modiolare_, _C. gowerianum_, _Belemnites
oweni_, _Ancyloceras calloviense_, _Nautilus calloviensis_, _Avicula
ovalis_, _Gryphaea bilobata_, &c.

On the European continent the "Callovien" stage is used in a sense that
is not exactly synonymous with the English Callovian; it is employed to
embrace beds that lie both higher and lower in the time-scale. Thus, the
continental Callovien includes the following zones:--

Upper Callovien / Zone of _Peltoceras athleta_, _Cosmoceras Duncani_,
(Divesien) \ _Quenstedtoceras Lamberti_ and _Q. mariae._

/ Zone of _Reineckia anceps_, _Stephanoceras
Lower Callovien < coronatum_ and _Cosmoceras jason_ and a lower zone
| of _C. gowerianum_ and _Macrocephalites
\ macrocephalus_.

Rocks of Callovian age (according to the continental classification) are
widely spread in Europe, which, with the exception of numerous insular
masses, was covered by the Callovian Sea. The largest of these land
areas lay over Scandinavia and Finland, and extended eastward as far as
the 40th meridian. In arctic regions these rocks have been discovered in
Spitzbergen, Franz Josef Land, the east coast of Greenland, and Siberia.
They occur in the Hebrides and Skye and in England as indicated above.
In France they are well exposed on the coast of Calvados between
Trouville and Dives, where the marls and clays are 200 ft. thick. In the
Ardennes clays bearing pyrites and oolitic limonite are about 30 ft.
thick. Around Poitiers the Callovian is 100 ft. thick, but the formation
thins in the direction of the Jura.

Clays and shales with ferruginous oolites represent the Callovian of
Germany; while in Russia the deposits of this age are mainly
argillaceous. In North America Callovian foss