SYNOPSIS OF THE BRITISH STRATA. 27 
uppermost place in the series in Sussex; sands and sandstones, with 
shales, and lignite, prevail in the middle ; while in the lowermost, 
argillaceous beds, with shelly marbles or limestones, again appear ; 
and, buried beneath the whole, is a petrified pine-forest, with the 
trees still erect, and the vegetable mould undisturbed! The upper 
clay beds and marbles form the deep valleys or Wealds of Kent and 
Sussex, and the middle series constitutes the Forest-Ridge. The 
Purbeck strata are obscurely seen in some of the deepest valleys of 
eastern Sussex ; they emerge on the Dorsetshire coast, form the Island 
or Peninsula whose name they bear, and surmount the northern 
brow of the Isle of Portland. On the southern coast of the Isle 
of Wight, the Wealden beds emerge from beneath the Greensand 
strata between Atherfield and Compton Bay on the western limit, and 
in Sandown Bay on the eastern; and their characteristic fossils are 
continually being washed up on the sea-shore. 
Tue Jurasstc on Ootitic Formation. (Wond. pp. 202, 
and 491). A marine formation of great extent and thick- 
ness, consisting of strata of limestone and clay, which abound 
in extinct species and genera of marine shells, Corals, Insects, 
Fishes, and terrestrial and marine Reptiles. Land plants 
of many peculiar types, and the remains of two genera of 
MamMatia. 
Subdwisions :— 
1. Portland Oolite. Uimestone of an oolitic struc- 
ture, abounding in ammonites, trigoniz, &c. 
and other marine exuvie. Green and ferrugi- 
nous sands—layers of chert. 
2. Kimmeridge clay. Blue clay, with septaria, and 
Upper Oolite 
of 
Portland, Wilts, 
mks: bands of sandy concretions—marine shells and 
Berks, &c. other organic remains—ostrea deltoidea. Beds 
of lignite. 
Middle Oolite 1. Coral oolite, or Coral rag. Limestone com- 
of posed of corals, with shells and echinites. 
Oxford, Bucks, 2. Oxford clay; with septaria and numerous fos- 
Yorkshire, sils. Beds of calcareous grit, called Kelloway- 
&e. rock, swarming with organic remains. 
