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5 or 10 feet, and containing an admixture of marine and freshwater mollusca. It is probably of the same age as the upper part of the Red Crag, as both deposits in places are overlaid conformably by the Chillesford Beds.
Mr. J. E. Taylor first drew prominent attention to the fact that at Bramerton, where two layers of Crag are to be seen, the upper division contained shells of a more northern or arctic character than the lower one; and this Upper Crag (or 'Taylor's Bed') was identified by the Messrs. Wood with the shell-bed above the Red Crag at Chillesford.
At the base of the Fluvio-marine Crag is a bed termed by Mr. John Gunn the Stone bed.' It rests on the Chalk the surface of which is occasionally bored by Pholas, and much furrowed and eroded. This bed yields numerous Mammalian remains, including Mastodon Arvernensis, Elephas meridionalis,Hippopotamus major, Rhinoceros leptorhinus, Cervus, Equus, Bos, Trogontherium Curieri, &c.1
The Fluvio-marine Crag beds are well shown at Thorpe, Postwick, and Bramerton near Norwich, at Bulchamp, Wangford (10 feet), and Thorpe near Aldborough in Suffolk; they have also been exposed at Bungay, as Mr. C. Reid has determined.
Among the common fossils are Tellina obliqua, T. lata, T. prætenuis, Cardium edule, Mytilus edulis, Mactra (several species), Litorina litorea, Conovulus pyramidalis, Purpura lapillus, Trophon scalariforme, T. antiquum, Turritella communis, Cerithium punctatum, Paludina media, Hydrobia ventrosa, Balanus crenatus, Fish-remains, &c. Scrobicularia plana occurs at Bramerton.
Jet and Beekite are occasionally met with in the Fluviomarine Crag.
1 Mr. Charlesworth gave the name Mammaliferous Crag to the entire series of beds, but it is now known, through the researches of Mr. Gunn, that the remains belong properly to the basement- or stone-bed, and that when found higher up in the series they show signs of being derived.
The Chillesford Beds (so named from Chillesford near Orford, in Suffolk) are subdivided by Mr. Wood, jun., into:
2. Chillesford Clay.
1. Chillesford Sand with Shell-bed.
The Chillesford Sand consists of micaceous sand with a shelly bed (not constant); this passes upwards into a bed of laminated micaceous clay, containing a few shells-the Chillesford Clay. The entire thickness is from 20 to 25 feet.
The fossils include Astarte borealis, Tellina obliqua, T. lata, T. prætenuis, Cardium edule, Cyprina Islandica, Nucula Cobboldia, Mactra ovalis, Mya truncata (= Mya bed of the Rev. O. Fisher), Purpura crispata, Litorina litorea.
Mr. Wood observes that the Chillesford Clay varies from a dark blue tenacious laminated clay, as at Aldeby and Easton Cliff, to a loamy micaceous sand, more or less interbedded with seams of laminated clay, as on the immediate west of Beccles, and on the south of Norwich, but it is easily recognizable everywhere.
In the pit at Bramerton, near Norwich, the following beds are seen resting upon the Chalk :
Between the Fluvio-marine Crag and Chillesford Beds at this locality is a layer of unfossiliferous sand about 12 feet in thickness, which Mr. Wood considers as equivalent to the Scrobicularia Crag of the Chillesford Section, which is as follows:
At Bramerton and Chillesford the Chillesford Beds, according to Mr. Wood, are marine; while at Easton Bavent, Burgh Kiln (near Aylsham), Coltishall, Horstead, Aldeby1 (Toft Monks), the Chillesford Beds are fluvio-marine in character.
The Chillesford Beds are overlaid by the Bure Valley Beds, which form a connecting link between the Pliocene and Glacial series.
Bure Valley Beds.
WESTLETON BEDS (Prestwich).
These beds the pebbly sands and pebble-beds-have been elucidated and described by Messrs. S. V. Wood, jun., and F. W. Harmer. The sands are mostly of a deep orange colour, and in them are seams and beds of rolled pebbles, which sometimes so predominate as to form masses of shingle: seams of laminated clay are not uncommon.
Near Halesworth and Henham they are described as forming true beaches, and at the latter place they attain a thickness of 25 feet.
The base of the Sands, when resting on the Chalk, is often occupied by an accumulation of shell-patches, known as Crag (Tellina-Balthica Crag): recognizable forms occur at Crostwick, Rackheath, Spixworth, Wroxham, Belaugh, Weybourn, Runton, and Trimmingham.
According to Messrs. Wood and Harmer they form the base of the whole Glacial series, and indicate the first setting
The fossils of the Aldeby Beds have been most carefully worked out by Messrs. W. M. Crowfoot and E. T. Dowson.
in of the great Glacial subsidence. They consider them to be unconformable to the Chillesford Beds, because in certain places along the Bure Valley and near Halesworth, the Chillesford Beds have been denuded prior to their accumulation. They are characterized by the first appearance in England of Tellina Balthica (solidula). The other fossils include Tellina obliqua, Cyprina Islandica, Leda obiongoides, Cardium edule, Litorina litorea, &c.
These beds range from the Bure Valley past Norwich to the neighbourhood of Southwold, and expand northwards into the Weybourn sand. In the Norfolk Cliffs they form a very variable series.
East of Cromer the sand becomes charged with lignite, and often laminated with bands of lignitiferous clay, in which condition it constitutes the Laminated beds' of Mr.
John Gunn. It passes up in places by interbedding into the Cromer Till.
In some localities near Norwich there is no definite line of separation between the Bure Valley Beds and the Chillesford Beds, and Fluvio-marine Crag beneath; and moreover they seem all of them to be so closely connected in their derivation and method of accumulation, that I prefer classing them together as one group-the Norwich Crag series.
FOREST BED SERIES.
One of the most remarkable deposits with which we are acquainted is the so-called Forest Bed of Cromer on the
1 Mr. Gunn considers these Laminated beds to represent the Chillesford Clay; he, however, uses the term Laminated series as a comprehensive term for all the strata from the Fluvio-marine Crag to the base of the Glacial series, and in the same sense as the term Norwich Crag Series is here used.
Norfolk Coast. This bed, so noted for the Mammalian remains which it has yielded, maintains a remarkable persistence wherever it has been observed, at about the same level, along the shore or fore-shore between Runton in Norfolk and Kessingland in Suffolk.
The Forest Bed occurs at the base of the Glacial series, and beneath the pebbly sands and the laminated beds (= Bure Valley Beds). But its precise relations to the lower portion of the Norwich Crag Series have not been determined. Its junction with the Chalk has never been observed, and therefore the total thickness of the series is unknown.
Its persistence thus along the coast is all the more remarkable if, as Lyell considered, there must have been a subsidence of the forest to the amount of 400 or 500 feet, and a re-elevation of the same to an equal extent, in order to allow the ancient surface of the Chalk with its covering of soil, on which the forest grew, to be first covered with several hundred feet of drift.
As the Forest Bed is intimately associated with several other beds of local interest, the term Forest Bed Series seems most applicable to these deposits.
To the indefatigable researches of Mr. John Gunn we chiefly owe our knowledge of the physical geography and the very interesting fauna and flora of the period when these beds were deposited. Some of his remarks I now quote.
The soil of the Forest Bed appears to consist of an argillaceous sand and gravel (pan), or a compound of both, and to have been deposited in an estuary. Bones of Elephas meridionalis, together with a great variety of deer and other mammals, sharply fractured, but not rolled, are found in it, especially in the gravel, which is called the "Elephantbed" on that account. These are associated with the bones of whales and fragments of wood, indicating that the Estuary