The triangular gap A in the Thick coal is filled up by a corresponding portion of the beds above the coal, consisting of shale and clunch, the lower part of which contains several courses of nodular ironstone, marked 1 in the figure. The strata in A are said to be "much broken and contorted, especially towards the apex. The ends of the strata are turned a little upwards. Two pieces of bituminous shale (2) are found on one side of it, which should under ordinary circumstances occupy the top of the coal." These latter are shown near the right hand of the bottom of the trough in the figure, and marked (2). The trough traverses the coal in a north-east and south-west direction, the bottom of the trough forming an angle with the horizon of 4° 30'.
In the portion of the Thick coal marked C, the lamination and stratification of the coal is uninjured, but in the part marked B, while the stratification is for the most part probably unaltered, as is shown by the "partings 10 and 13 continuing through it almost uninterruptedly, the "lamination of the coal is totally destroyed, and the coal has the appearance of a paste made up of coal dust and very small coal. It appears to have attained its present consistency from compression and not from heat."[1]
Fig. 27
A. The Trough.B. The compressed Thick coal.C. The unaltered Thick coal.
Fig. 27 is a more extended representation of a side of the same gate-road on a smaller scale, that of 60 feet to the inch, its total length being about 150 yards. It is reduced from a much larger drawing of Mr. Johnson's, which was drawn to scale from very careful measurement, every fissure and flexure being as nearly as possible exactly represented.
The two drawings given in Figs. 26 and 27 were taken, I believe, in consequence of the explanation I proposed to Mr. Johnson, to account for the appearance mentioned first (p. 194), that in which the trough did not end in a point downwards, but was still eight
- ↑ Mr. Johnson's notes.
