Page:The South Staffordshire Coalfield - Joseph Beete Jukes - 1859.djvu/25

Rh beds in the Permian formation. There are, however, we believe, no brick-red sandstones like that of the Bunter, and scarcely any quartzose conglomerate to be found in the Permian formation; whenever, therefore, we get the above-named doubtful beds in our district, we can determine their geological horizon simply by their place with regard to the soft red and mottled sandstones and quartzose conglomerates. There are two parts of the district from the examination of which it is possible to arrive at a tolerably complete notion of the structure and sequence of the Permian rocks, namely, the country about the Lickey and Clent Hills, and the neighbourhood of West Bromwich.

The country about the Lickey and Clent Hills.—The south end of the Lickey Hill, that on which the obelisk stands, is composed of the quartzose conglomerates and red sandstone, believed to be there the base of the New red. On the northern end of the Lickey, about Square Coppice, as also on all the summits of the high ground of Segban, Romsley, Frankley Beeches, and the higher parts of the Clent Hills, where we get what appear to be the highest of the Permian beds in their respective localities, we find these beds to consist of a remarkable trappean breccia. This breccia is principally made up of angular fragments of trappean rocks, but almost equally angular fragments of many other rocks are found in it. A good section of this trappean breccia is shown in a road cutting just north of the brook in the lane leading from the Bell Inn, at Northfield, to Bangham Pit. The matrix of the breccia is here a brown sandstone, in places calcareous, interstratified with thin bands of marl. The imbedded fragments, some of which are slightly rounded, but the majority remarkably angular, vary in size from mere grains to blocks a foot or a foot and a half in diameter; they consist of porphyritic trap in many varieties (but no basalt or greenstone) of sandstone of various kinds, of quartz-rock, and of Silurian limestone and sandstone, some of which is certainly Llandovery sandstone, not at all altered. There are slabs of these Silurian limestones and sandstones at least 1 foot to 1½ foot square and 5 or 6 inches thick, with their edges scarcely at all rounded. The whole mass has a well-stratified character, and in some places is firmly compacted together by carbonate of lime, but in others is more or less incoherent. The slabs of Llandovery sandstone are now easily split into thinner flags by a very slight blow, and some of them seem to be already so separated in the ground. This, together with their angular character, inclines me to believe that they have not travelled many yards from their original site, and that a boss, or peak, or ridge of the Silurian sandstone lies concealed under the Permian rocks somewhere close by.

The following rough sketch (see Fig. 3), drawn to scale with a measuring tape, will give an idea of the mode of occurrence of these breccias as seen in the bank of the lane above spoken of.