Page:The South Staffordshire Coalfield - Joseph Beete Jukes - 1859.djvu/198

180 arrived at the conclusion that the boundary between the New red and that considered to be Permian was not a fault but a natural boundary, a conclusion in which Professor Ramsay believes him to be correct.

We are, therefore, left to mere conjecture as to the lie and position of the Coal-measures below the red rocks east of the line up to which they have been worked.

It will be more convenient now if we go to the northern end of the eastern boundary fault and trace it southwards. In the Brereton colliery they drove through the fault, and found some part of the conglomerates of the New red against the fifteenth coal at a depth of 460 feet. New red conglomerates rest upon the Coal-measures here on the western side of the field without the intervention of any fault, but it does not follow that they are the same beds of conglomerate, and it is quite possible that those found at this depth in the workings are much higher in the series than those found at the surface at Stile Cop and the neighbourhood. The downthrow of the fault, therefore, may be a great deal more than that 460 feet, and there may be a succession of step-like downthrows outside it again. One such step-like downthrow was observed in a gravel pit at no great distance from the spot. Starting from this point along the line drawn on the map to the southward, we have abundant evidence of "Red rock" on one side, and of Coal-measures on the other, lying just below the surface of the ground in a nearly horizontal position. The Red rock is the ordinary Red sandstone of the New red formation. In Beaudesert Park it is apparently one of the soft red sandstones that were formerly called Brick red sandstone; about Cannock Wood the beds are white and brown sandstones, and on Old Lodge Hill are some excavations in red marl that appear to be just the bottom beds of the upper subdivision of the formation, the Red marls. From this point scarcely anything can be seen or known for about two miles, till we arrive at the Hammerwich colliery just east of the dam of the reservoir. In the coal-pits there they drove to the east, and struck the Red rock fault just under where the feeder falls into the new branch of the canal. The Red rock is seen in the canal to be the lower subdivision of the New red sandstone, consisting of Red sandstones and conglomerates, and the coals are known to be in the lowest portion of the Coal-measures. So far we have seen no Permian rocks, though it is quite possible that rocks of that formation lie concealed under the New red sandstone, and between it and the Coal-measures on the downcast sido of the great fault.

Nevertheless, no rock considered to be Permian makes its appearance at the surface between the New red sandstone and the lower rocks, till we come south of Aldridge to the neighbourhood of Hay Head and Great Barr, which has been before described.

Somewhere about the Brown Hill, however, it would appear that a split takes place in the boundary fault, and that a branch is sent off into the Coal-measures, ranging down the valley by Clayhanger, and thence to the southward, until it probably meets with or passes into the Linley and Daw End fault that cuts off the Walsall Silurian rocks.

The bottom Coal-measures crop, as before shown, all along the region of Pelsall Heath and the Brown Hills, dipping to the west. East of this outcrop, however, nothing is to be found but the red clays which are now believed to belong to the upper part of the Coal-measure series above all the workable coals. 'These may be seen lying horizontally or dipping at a very gentle angle to the northward or north-westward at Catshill, and all down by Walsall Wood to Stubbock's Green. From under these red clays the dark coal-bearing measures then rise to the southward towards Linley and Aldridge.