A Peat Bed in the Drift at Oldham

Abstract

IN NATURE, vol. xxii. p. 460, there is a letter by Mr. Jas. Nield, giving an interesting description of unique, or nearly unique, appearances in the boulder clay near Oldham. It appears that this glacial deposit has one or more beds of peat, or fragments of peat, intercalated along with it at various depths, leading to the inference that the day had been stirred up and the fragments of peat had in some manner been mixed with it. That peat bogs, or surface black peaty mould, had existed at no great distance is a conclusion forced upon us, and that the action of ice and snow, probably during a submergence, had mashed up the clay and distributed the peat amongst it. The boulder clay, and the scratched mountain sides, and the travelled fragments of rock, do not extend over the whole of England. It used to be said by geologists that the effects of a severe Arctic climate could not be detected south of a line drawn across the country from London to Bristol; by which it was inferred that all the land north of that line had been under water, subject to the influences of snow and floating icebergs, and all the country South of it above water and clear of those influences. Since then the large granite boulder on the shore of Barnstaple Bay, estimated to weigh ten tons, has been brought more prominently under our notice by Mr. W. Pengelly (Trans. Dev. Assoc. vi. 211), and several others by Mr. T. M. Hall (ld. xi. 429), discovered by excavation. All these are travelled blocks, and probably ice-borne. Many attempts have been made by ardent and intelligent students of late years to detect proofs of glacial action further south, and even to the shores of the British Channel, but hitherto with doubtful success. There lies on the greensand of Haldon, near Exeter, and on the Blackdown Hills, stretching away towards the south-east corner of the county of Devon, a stratum of tough yellow clay full of white flints, mostly angular. About Haldon and eastward over Pitminster and Churchstanton, many white quartz rounded pebbles, foreign to the accompanying beds, are met with. Farther south, between Honiton and the sea, this stratum of flints and clay in some places is seen to be from forty to fifty feet thick, and the best section of it is in the gravel pits near the cliff on Peak Hill, on the west of Sidmouth. By some persons this deposit has been regarded as the thinned-out edge of the plastic clay formation, containing the remaining flints of the washed-out chalk, still found more perfect at Beer Head, a few miles east. Whether it was this, or whether it was a boulder clay, so called, it is well to remark that, though thickest on the flat tops of the hills, it seems to lap down over their sides, as if it had been deposited after the valleys and the elevations had come to their present conformation; and at two places at least to be visible in the valley of Sidmouth—one under the great blocks of breccia in the orchard near the brook on the Boomer or Boughmoor Estate, and the other on a subordinate hill in a grass field, at about 200 yards from Jenny Pine's Corner, walking down the new road towards Cotmaton, and on the right-hand side. Most of this latter patch of clay and flints was dug away two or three years ago to assist in forming the new road.