The drift-deposits of Yorkshire, Lincolnshire, and the Eastern Counties, have been most carefully investigated by Mr. S. V. Wood, jun., assisted by the Rev. J. L. Rome and Mr. F. W. Harmer. The following table exhibits their classification of the deposits:- Hessle (Boulder) C'ay. Hessle gravel (Kelsea Hill bed). Nar valley beds. Older Post-Glacial. Gravels and brickearths [connected with the denudation of the Glacial beds during their emergence from the great depression]. Upper Glacial. Middle Glacial. Lower Glacial. The purple (Boulder) clay of Yorkshire without chalk, passing down into The purple (Boulder) clay with chalk, and containing the Bridlington shell-bed. The great chalky (Boulder) clay. | Sand, Gravel, and brickearth, with occasional seams 1of boulder clay. Contorted Drift. Bure Valley Beds : sée p. 290. Prof. Phillips contended for the Pre-Glacial age of the Hessle Beds, but on the authority of Messrs. Wood and Rome they will here be treated of as Post-Glacial. a relic of this destroyed tract. The account is very precise, indicates a sufficient knowledge of the general nature and localities of the formation, and is such as to render the testimony very respectable; but the point is so important that further enquiries are desirable. The Chalk is described as regularly interstratified with flints; and the surrounding district being entirely occupied by the ferruginous sands of the Inferior Oolite, it is not easy to conceive that it could have afforded any rock which could have been mistaken for Chalk. Another detached patch of Chalk is said, in the same place, to exist near Stukely in Huntingdonshire on the banks of the Turnpike Road, but no particulars are given, and here soft varieties of other calcareous beds might be confounded with this substance.' LOWER GLACIAL BEDS. LOWER BOULDER CLAY. The Lower Glacial Beds are estimated to have a maximum thickness of about 200 feet. In no other part of England and Wales are these Glacial Beds so well shown as in the cliffs along the Norfolk coast, which in places rise to a height of 200 feet. Cromer Till. The Cromer Till consists of a dark blue or grey sandy clay with numerous small pebbles of Chalk and other stones, and occasional large boulders of granitic rock, greenstone, and grit. Many of the stones show glacial striæ. It generally rests upon the Bure Valley Beds, with which there appears in places to be some evidence of interstratification. It is not altogether persistent in the coast-section between Cromer and Happisburgh, but it forms a band that can readily be recognized. The junction with the beds above is not always very distinct; in some places there is a passage, in others there is evidence of local erosion, and the overlying beds occupy hollows on the surface of the Till. Inland it is inseparable from the Contorted Drift. Contorted Drift. This deposit consists essentially of a brown stony loam, sometimes well stratified and containing seams of gravel and sand, at others containing seams of chalky loam or boulder clay, and exhibiting most violent and remarkable contortions. Messrs. Wood and Harmer have noticed its occurrence in Suffolk, as a reddish-brown brickearth, resting on the pebbly sands (Bure Valley Beds). It is, however, in the cliffs between Eccles and Wey bourn that it can be best studied, and it there exhibits almost every variety of condition and contortion. The main. portion of the cliffs is indeed made up of this usually brown loamy deposit, which rests on the blue Cromer Till. The contortions become conspicuous west of Mundesley, and thence near to Cromer, and between Cromer and Weybourn, seams of very chalky loam or boulder clay occur here and there in isolated irregular and lenticular masses. These are sometimes worked inland for lime. Between East Runton and Woman Hythe are three large masses of transported Chalk which, by the weight of the bergs carrying them, have sunk in some cases into the subjacent Till, and even into the Weybourn Sand (Bure Valley Beds). The Contorted Drift is extensively worked for bricks around Norwich, North Walsham, Aylsham, and many other parts of Norfolk: it is sometimes called the Norwich Brickearth. In Suffolk it has been observed at Somerleyton, Beccles, Harleston, Woolpit, Boxted, Sudbury, Kesgrave, Hasketon, &c. Messrs. Wood and Harmer attribute the formation of the marly portion of the Contorted Drift to a discharge of ground-up Chalk from the débouchure of a Glacier that occupied the Chalk country of Cambridgeshire and West Suffolk; the brickearth which forms the easterly development of the Contorted Drift being due to a river discharge in that part; the two sediments intermingling in the intermediate area, and producing the alternations of marl and brickearth there presented by this formation. The detached masses of the marl were, they consider, introduced into the brickearth portion of the deposit by the agency of bergs, which, breaking from the Glacier and grounding, picked up masses of the marl forming over the sea-bottom in that part of the area. These masses the bergs carried out into the area where the brickearth was accumulating, and grounding again, imbedded them in the brickearth, and even in the subjacent Till and Weybourn Sand, contorting the beds in the process. From detached portions of this marl, which they have found as far south as Claydon, near Ipswich, and Stanstead, near Lavenham, in Suffolk, they infer that this deposit covered the West of Suffolk and Norfolk, but underwent great denudation in the former part by the waters of the Middle Glacial sea, the sands of that sea, west and south of Diss, lying up to bosses of it in some parts, and overlying it in others. The remarkable contortions of this Drift were well pictured by the late Mr. Samuel Woodward in his Geology of Norfolk.' The contortions have been attributed partly to the thawing of masses of ice which had been fixed among the beds during their deposition, but more generally to the action of stranding icebergs. MIDDLE GLACIAL BEDS. MIDDLE DRIFT. BOULDER SANDS AND GRAVELS. (Prestwich.) The Middle Glacial beds consist of gravel and sand with occasional beds or seams of chalky Boulder Clay, as near Hertford. The gravel is composed to a great extent of Chalk flints both subangular and rolled, and pebbles of quartz and quartzite. Its thickness is variable, being sometimes 15 or 20 feet, at others as much as 40 or even 70 feet. In some localities sand predominates, in others gravel, and occasionally a good deal of brickearth is associated with the beds. The sand sometimes contains pebbles of Chalk. The gravel contains a great many rolled fossils derived from many different formations, but chiefly from those of Secondary age. The pits at Muswell Hill and Finchley, owing to the labours of Mr. N. T. Wetherell, have yielded a large number of specimens. (See fig. 22, p. 314.) In some places in Essex the Middle Glacial gravel is very pebbly in nature, which in Mr. Wood's opinion was probably due to the proximity of Eocene pebble-beds, whether belonging to Reading Beds, London Clay, or Bagshot Eeds. In the neighbourhood of Hertford the Tertiary beds are capped by a pebbly gravel composed chiefly of flint and quartz pebbles. This is very distinct from the more mixed gravel on the Chalk, and has been termed by Prof. Hughes the gravel of the higher plain,' to distinguish it from that in the lower grounds. He suggested that it might be PreGlacial. It occurs also at Barnet, Totteridge, &c. Along the borders of the Thames Valley it is often a matter of great difficulty to distinguish between the Middle Glacial gravels and those formed by the river in great measure from their destruction: such is the case near Great Marlow, also at intervals along the Valley as far as Southgate. At Danbury, in Essex, the gravel occupies a high elevation, but the hill is coated with gravel and not formed by it, as Mr. W. H. Penning has traced the London Clay exposed in gullies near the hill-top. Deposits of loam and brickearth are associated with the gravels on the Chalk tracts of Buckinghamshire and Hertfordshire, and sometimes with those on the London Clay; but it is not possible always to fix the ages of the deposit. Thus, at Chelmsford there is a deposit of brickearth, which may be of Glacial age or Post-Glacial. Near Yarmouth, Messrs. S. V. Wood, jun., and Harmer have obtained from these Middle Glacial deposits shells of a southern aspect, including several extinct Crag forms, which tend to separate them from the Middle Sands of Lancashire, in which none but recent shells have been found. These include Buccinum tenerum, Fusus antiquus, F. scalariformis, Nassa incrassata, Turritella incrassata, Cerithium punctatum (tricinctum), Pectunculus glycimeris, Nucula Cobboldiæ, Astarte borealis, Tellina obliqua, Mya arenaria, &c. It appears, in Mr. Wood's opinion, to have been a littoral marine deposit, and to be unconformable to the Lower Gla |