Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/294

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Mr. Bakewell on the Coalfield near Manchester.

vation. There is indeed a dyke in one part of the field, filled with a stone nearly similar to the red rock, but it does not affect the position of the strata on either side of it.

Fourteen hundred yards to the north of the Bradford coalfield, and separated from it by the red sandstone, is the coalfield of Droylsden. The first coal that rises there at the distance of 60 yards from the red rock, is similar to the bed which rises at the distance of 350 yards from the perpendicular coal in the Bradford field.

In the middle figure of Pl. 2.

A A represents the length of the Bradford coalfield.

B B its breadth.

C C C C C. different beds of coal which rise to the surface, and would be visible along their line of bearing parallel to AA., but are concealed by soil and gravel, except on the banks of the river Medlock.

P P the perpendicular bed of coal.

L L the limestone.

R R R the red sand rock.

S S two beds of coal 20 inches thick, one of them situated in Droylsden coalfield.

The lower figure of Pl. 2. represents a section of the same strata on a vertical plane perpendicular to A A.

Plate 2, Fig. 3.

It appears probable that the strata in these two fields were once united, and have been separated by some convulsion of nature; in consequence of which the red rock has been interposed like a wedge between them, a sliding motion being given to the strata by lateral pressure; for a force acting in a direct line from above or beneath could not produce the bending or folding of the four-feet coal.

The red sandstone has not, I believe, been sunk through in any part of our island, so that its immediate substratum is yet unknown.

If it should prove to be the metalliferous limestone, it will occupy the same geognostic situation as the red shale of Derbyshire and