1030 
m. PENGELLT ON THE LIGNITES AND 
Newly exposed surfaces of the laminse of the lignite are sometimes more or less 
covered with stellate crystals of selenite. Their beauty is very striking, and is enhanced 
by contrast with the dull dark surface on which they lie ; unfortunately it is by no 
means durable ; the stars first lose their brilliancy, after which many of them disappear 
altogether. 
Fragmentary pieces of lignite occasionally occur in the “ coal-beds” as well as in the 
clay ; some of them are perfectly flat slabs, of various sizes, having sides and ends as 
true and angular as if they had been something more than rough-hewn in a carpenter’s 
shop. Others have an appearance resembling stranded drift-wood; I found a well- 
marked piece of this character in the 72nd bed. 
The flattened form which the “board coal” commonly assumes is by no means con- 
fined to the lowest beds ; it is as characteristic of the 5 th, or uppermost, and of that 
portion of it which most nearly reaches the surface, as of any bed in the pit sections. 
As pressure must be regarded as essential to this flatness, though probably not its sole 
cause*, it seems impossible to avoid the conclusion that much of the superior portion 
of the deposit has been removed by denudation. It must not be supposed, however, that 
all samples of “ board coal,” taken from any one bed, are equally flattened. Examples 
occasionally present themselves, of portions of stems and branches, in which the original 
cuiwature of outhne is not entirely obliterated — the transverse section distinctly showing 
the rings of annual growth converted into ellipses of great excentricity. Good instances 
of this have been met with in the lowest beds. 
The stones so abundant in the “ Head,” or uppermost division of the pit sections, are 
sufficient to show that it was formed under conditions dissimilar to those which produced 
the two lower series. Moreover, it lies unconformably on them. Nowhere in the 
excavation do the lignite and interstratified beds reach the surface ; they are cut off at 
distances varying from 3 to 7 feet below it, as is shown in Plate LIII. 
It has already been stated that the stones of the “ Head ” are generally angular or 
subangular ; occasionally, however, some occur that are much rounded. They vary in 
size, from blocks upwards of a foot in mean diameter to pieces not larger than hazel- 
nuts. On Bovey Heathfield they are fragments of granite, metamorphic rock, car- 
bonaceous grit, and trap, with a very few of flint and chert. The two last increase in 
number eastward — that is, with increased proximity to the Cretaceous district, — and in 
some localities are even more abundant than other detritus. 
In no instance have I found or heard of limestone-fragments on the Bovey Heath- 
field. A transporting current from the north or north-north-east seems to be requhed to 
meet the facts of the case. Were it not for the samples of flint and chert, a movement 
from the west or north-west, or even south-west, might have supplied the materials. 
No agent progressing from any part of the compass between the north-east and south- 
west, through south, could have furnished the granite-blocks or failed to transport large 
quantities of limestone-debris. On the whole I incline to a transportation fi'om a 
* See Hatchett in Philosophical Transactions for 1804, Part I. p 397. 
