Mr. Cumberland on the Strata near Bristol . Ill 
Here commences a new series, lofty, ascending from a deep 
valley, and here the fine oolite beds end. 
*This series is called the Black Rock y from its being discoloured 
by organic remains, which probably contained much oil, as in parts 
where they most abound it has been collected in a liquid state. It 
is dark coloured and pungent, and the quarry-men make use of it 
for sprains and rheumatic complaints. It is a beautiful marble, both 
where the encrinital and coral remains are predominant, and also 
where it is of a deep black; and would be valued both by turners 
and masons were it generally known, as it takes a fine polish. 
Occasionally, in the centre of the beds, are found large patches of 
red limestone, quite irregular, and generally crossing the stratum. 
At the commencement is a sharp valley; but the rocks rise at an 
angle of 43 degrees at least ; and the first bed is a grey limestone, 
with encrinites, while all indeed, more or less, have this character ; 
but in the first bed they appear most to abound at the extremities 
of each surface. 
No. Ft. In. 
258. Divided into three parts inclusive, above . . 24 
The lowest diminishing as it rises, as indeed all do, and 
terminating in a fine exactly even line of separation, of 
about one inch thick, which extends from the bottom to 
the summit in an angle of eighty degrees. 
259. A bed quite regular but diminishing . . . . 5 & 
A little upwards, the whole dark grey with occasional 
heads, and parts of encrinites, the lowest end a little 
divided in cracks. 
* Here a considerable spring issues constantly from a cavity in the bed of the river Avon, 
at about half low water mark. It is cold. These springs are all marks of what the miners 
here call Swallow-its, in the upper part of the hills, and all fail in dry weather. One of 
these cavities was opened at Red land three years ago, that was 200 feet long and des- 
cending ; but it was a mere channel, not a reservoir. 
