apt to observe any distinction between the grey shales of the coal- measures and the shales of the Silurian series. Where the latter also are at all hard, or slightly arenaceous, the miners are likely to call them "rock binds," and we are thus liable to class them as Coal- measures. Mention, too, is sometimes made in the sections of a " blue rock now, whenever I have seen any beds thus described, I have always found them a compact slightly arenaceous clay rock, so greatly indurated as to form a hard tough stone : and, in sinking a shaft, the Silurian shale of this neighbourhood would be likely often to have these characters, and thus be called by the miners "blue rock." Whenever there is a white or strong brown rock mentioned, I should always consider it as part of the Coal-measures, because I have never seen or heard of any sandstones of that colour in the Silurian shales of this district ; and if it were limestone rock, they would almost cer- tainly have described it as such.
With these remarks I now lay before the reader the following ten extracts from pit sections, beginning at the most southerly, and pro- ceeding to the north and east : —
Bottom coal | 9 | 2 | |||
Rock and clunch | 39 | 0 | 68ft | ||
Ironstone measure may = Blue flats | 7 | 0 | |||
Fire-clay, rock, and pebbly rock | 22 | 0 | |||
Blue clunch | 4 | 0 | |||
Bavin and limestone | 72 | 0 | |||
153 | 2 |
(Vert. Sects., sheet 18, No. 36.)
FT. | IN. | |
Bottom (?) coal | 1 | 6 |
Fire-clay, black ground, rock binds, and rock | 60 | 0 |
Bavin (Silurian shale) | 69 | 0 |
Limestone | 27 | 0 |
Limestone | 24 | 0 |
181 | 6 |
(Vert. Sects., sheet 16, No. 13.)
FT. | IN. | ||||
Bottom coal | 11 | 9 | |||
Fire-clay, rock, | 37 | 0 | 71 ft. | ||
Singing coal | 4 | 0 | |||
White rock and pebbles | 30 | 0 | |||
Blue binds | 130 | 0 | |||
212 | 9 |
(Vert. Sects., sheet 16, No. 12.)
FT. | IN. | ||||
Bottom coal | 9 | 0 | |||
Fire-clay, black ground, and rock | 80 | 0 | 92ft. | ||
Ironstone (Blue flats?) | 4 | 6 | |||
Strong pebbly light coloured rock | 7 | 6 | |||
Strong blue rock | 3 | 0 | |||
137 | 0 |