TA THE MEDALS OF CREATION. Cuap. V. 
aspect the characters of a coal-field, that some years since 
extensive works were undertaken in Sussex, in the expecta-_ 
tion that coal might be obtained of suitable quality for 
economical purposes. The search was unsuccessful, but the 
attempt deserves not the censure that was bestowed upon it, 
in the infancy of geological science ;* for experience has 
since shown, that although the true coal-measures are 
only found beneath the Triassic and Permian formations, 
good combustible bituminous coal is not necessarily re-— 
stricted to any period or series of strata, but may occur 
wherever the local conditions were favourable to the accu- 
mulation and bituminization of vegetable matter. In fact, 
the coal-fields of the north of Germany are of the Wealden 
epoch ; and this coal more closely approaches in its che-— 
mical characters the black-coal of the ancient carboniferous 
formations, than any of the lignites and brown-coals of — 
the tertiary strata. Some of the beds are highly bituminous, 
especially those of Schaumberg, and of the principality of 
Biickeburg, which may rank with the best English Newcastle 
coal ; but those layers which are derived from coniferous 
trees and plants are more laminated, and somewhat resemble ~ 
the brown-coal. These deposits have originated for the 
most part from carbonized conifers and cycads, with a few 
ferns and lycopodiaceze, or club-mosses. 
The brown-coal of Hohen-Warte by the Osterweld, is — 
chiefly formed of the Abies Linkii, and Pterophyllum — 
Lyellianum, whose leaves and twigs, closely impacted 
together, are generally of a brownish colour, have a glossy 
surface, and, when soaked in water, are perfectly flexible. 
The other modification of Wealden coal appears to have 
undergone a greater degree of pressure, and of exclusion 
from the atmosphere ; no ligneous structure is apparent, 
but indistinct impressions of leaves are perceptible, and 
these are chiefly of ferns and club-mosses. This coal has 
* See Sir J. F. W. Herschel’s Discourse on Nat. Phil. 
