Page:VCH Herefordshire 1.djvu/75

From Wikisource
Jump to navigation Jump to search
This page needs to be proofread.

GEOLOGY Permian System In Herefordshire the only rocks which are probably of Permian age are certain conglomerates at Haffield, at the southern end of the Malvern Silurian tract, and at Whippets in the Cradley district. The conglomerates in the neighbourhood of Haffield are composed of well-rolled fragments of Uriconian and Silurian rocks imbedded in a dark- red sandy matrix — the pebbles having no doubt been derived from the partial destruction of rocks in the neighbourhood. Phillips was the first to suggest the term ' Haffield Breccia,' '* and while in 1 848 he regarded the accumulation as basal Triassic, later he grouped it with the Permian. Symonds speaks of it as Permian,'^ and Professor Groom thinks that this is its age ; but Mr, Wickham King prefers to consider its precise date an open question, as certain of the Bunter and Keuper deposits much resemble it in lithic structure.** As Professor Groom, however, points out, if the Haffield Breccia is basal Bunter, it is an older Triassic deposit than any known in this country. Until more evidence is forthcoming to prove the contrary, the Haffield Breccia may be regarded as Permian, and equivalent to the well-known Trappoid Conglomerate of the Midlands. The Permian rocks of England, west of a line drawn north and south along the Pennine axis, appear to have been formed in a land-locked stretch of water which had connexion with the main sea to the east by means of a strait situated near the present southern termination of the Pennine Range. Professor Groom is of opinion that the geographical distribution of the Haffield Breccia was once far greater than at the present. This is highly probable, but it is impossible to indicate its original limits. Triassic System With the Permian our account of the rocks which belong to the Palaeozoic Group closes. The third and last great group is the Neozoic. It comprises a number of systems, series, &c., the oldest series being the Bunter. In Herefordshire the Bunter rocks are bright-red sandstones often called — after the village in the neighbourhood of which they occur — the Bromes- berrow Beds ; but in this county they occupy a very small area — barely half a square mile in extent. Once no doubt they extended farther into the county, passing over the Haffield Breccia ; but except for the reddish colour with which they have stained the contiguous Silurian rocks, all evidence of their more extended distribution has been removed. No fossils have been obtained from the rocks in Herefordshire or from the succeeding Keuper deposits, which occupy an area as small as that where the Bunter rocks prevail. In Germany, between the Bunter and Keuper Series occur richly fos- siliferous marine beds called the Muschelkalk ; but although they may be, and probably are, represented in point of time in this country, they have not been identified on the test of included organic remains. " Mem. Geo/. Surv. ii, pt. i (1848), pp. 1 1 1-12. ** Records of the Rocks (1872), pp. 417-18. ^ Quart. Joum. Geol. Soc. Ivi (1961), p. 196. 27