it with Mr. Thompson. The black batt containing nodules of ironstone, which usually lies below the coal, seemed to thicken upwards very gradually, and the three lower coals ended against it with a distinctly rounded outline, and without any mark or sign of disturbance, either contemporary or at a subsequent period. So gradual was the rise of the lower batt, that at one part of the gate-road it required 18 feet of horizontal distance to rise 2 feet 9 inches vertically. In other words, the slope was not so much as 1 in 6 (=9°)
Fig. 9.—Section of a "swell" in the Baremoor colliery.
a. Bottom part of Thick coal.
1. Patchells.
2. Sawyer.
3. Slipper.
4. Benches.
b. Swell, or horse's back, consisting of dark clunch, (black clod).
c. Large irregular nodules of ironstone.
Fig. 9 is a sketch of the transverse section of the swell, from a rough drawing and measurement on the spot.
After continuing for a few feet in the Patchells, the crest of the swell gradually descended, letting in the lower coals again, the fas two sides of it being nearly, if not quite, symmetrical. I do not know what was the longitudinal extension of this particular ridge, but they are often met with one or two hundred yards long; and sometimes one or two will run close together, parallel to each other, for that distance.
It 1s, of course, possible that they might in some cases have been caused by disturbance anterior to or contemporary with the formation of of the lower part of Thick coal, though, in that case, the beds below would be equally bent, which is not. I believe, found to be the fact. It is, however, much more likely that they were merely long ridge-like accumulations of mud or sand piled up in the water in which the measure forming the floor of the coal was deposited. Theoretically, they are important as showing that whatever was the process of the formation of coal, it was in this case necessarily formed in a strictly horizontal position. The lowest bed of the Thick coal (see Figure No. 9) ended against the very gentle slope of the swell, and no bed was formed over it until a sufficient accumulation of coal had taken place around it to make a floor level with its crest. The minute partings of shale or earth between the different beds of coal in the Baremoor colliery sensibly thickened as they approached the swell and coalesced with it. In a practical point of view these swells are worthy of study, inasmuch as they often diminish or destroy the value of a tract of coal. They very frequently occur. I believe, in all coal-fields, but it is not always that they can be so well examined and understood as in the Thick coal of Staffordshire. They are commonly spoken of by the colliers as faults, a term likely to lead all concerned into great
