THE ISLE OF PORTLAND. 
837 
were standing erect, evidently upon the very spot 
on which they grew, and where they had remained 
undisturbed amidst all the revolutions which had 
subsequently swept over the surface of the earth.* 
“ The dirt-bed extends through the north of the Isle 
of Portland, and traces of it have been observed in 
the coves at the west-end of Purbeck ; and a stra- 
tum, with bituminous matter and silicified wood, 
occurs in the clifts of the Boulonnois, on the oppo- 
site coast of France, occupying the same relative 
situation with respect to the Purbeck and Portland 
formations. A similar bed has also been discovered 
in Buckinghamshire, and in the Vale of Wardour, 
proving that the presence of this remarkable stra- 
tum is coextensive with the junction of the Port- 
land and Purbeck strata, so far as they have hitherto 
been examined.”t 
Above the dirt-hed are thin layers of limestone, 
the total thickness being about eight feet, into 
which the erect trunks extend, but no other traces 
of organic remains have been noticed in them. 
O 
These limestone beds are covered by the modern 
vegetable soil, which scarcely exceeds in depth the 
ancient one above described ; and instead of giving 
support, like the latter, to a tropical forest, can 
* These liighly interesting facts were first pointed out bv Mr. Web- 
ster (Geological Transactions, 2d series, vol. ii.). The fossil plants 
have been beautifully illustrated by Dr. Buckland (Geol Trans. 2d 
series, vol. ii.), who, in conjunction with Mr. De la Beche, has sub- 
sequently laid before the Geological Society a masterly paper on the 
geological phenomena of the Island of Portland, and of the vicinity 
of Weymouth. — Gcol. Proceedings, 1829, 1830. 
t Viilc Geology of Hastings, p. 76. et seq. 
/ 
