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ON THE FORMATION OF THE WAVENEY VALLEY.
ON THE FORMATION OF THE WAVENEY VALLEY. BY WILLIAM FOWLER,
Hon. See. Beccles Eist. Soc.
IT is assumed that the study of Geology is dry but, like many other things taken for granted, such is incorrect; for, when the natural curiosity of the individual is awakened, the constituency of his own immediate neighbourhood of the land he inhabits forms an engrossing subject. The natural desire, shown by every child's mind, to know the Contents of a wrapped and sealed parcel, is developed in the adult's patient enquiry into each of the crusts covering the earth's surface. The sister counties of Suffolk and Norfolk, divided forfifty-threemiles by the River Waveney, form the paradise of those who study the Pliocene deposits of the Tertiary epoch. That is to say, we live in the most youthful of all English counties; no others have the later strata, that constitute the geological history of England, so well preserved upon their surface ; and, of all such, the Crag beds of these twins are those of outstanding interest. On the other hand the older rocks are entirely wanting. The Old Red Sandstone of Devon and Scotland, where it is computed to be three thousand feet thick ; the Milstone Grit of Lancs and part of Yorks ; and the great Limestone series of Derby, which is no thinner, do not here outcrop with the exception of a few wandering erratics and, on the coast, in numerous quite small stones. The solid Geology of our East Anglian area is chalk ; and this extends from the Downs of southern England throughout both our counties to the Continent: here, in the Waveney Valley, it lies between sixty and ninety feet below the surface.* West of us this chalk outcrops from Haverhil to Bury and thence continues the line to the North Sea, perpetually dipping eastwards below later strata and, in some places, as abruptly as forty-eight feet in a mile : consequently it is invisible anywhere in our Valley. Chalk was laid upon a sea-bottom, hence it was probably at first level over both our counties ; later the western part was uptilted by a crust-creep. From the ridge thus formed, many hundred feet have been weathered and eroded by the tremendous glaciers that travelled in later years from the north and north-west during the Great Ice ages. * At Puddingmoor Waterworks in Beccles a boring of March 1929 showed : 4 feet of loam ; over 6 of brown-sand and stones ; below were 10 of peat, 2 of grey sand, 9 of sand mixed with gravel, 12ÂŁ of grey-sand and clay (probably the Chilesford Bed), 13J of grey-sand with shells, and finally 318 feet of chalk containingflints,and continuing to the boring's total 375 feet.
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Material thus eroded, and now mixed with the detritus of the glaciers themselves, yet lies scattered over the surface of both counties ; a scrap of it was doubtless the chalk-marl of a pit in Aldeby, for the removal of which in order to improve their land the local Black Monks sought the sanction of their patronal Prior at Norwich about 1203. The greatest thickness of our chalk is twelve hundred feet at Carrow near Norwich ; that at Beccles is rather over eight hundred, or fully a dozen times the height of its church tower. Mr. Clement Reid has shown that no doubt can exist respecting the continuity of East Anglia with the Continent at this chalk-period, by means of a land surface across the later North Sea. His map indicates a river, the Waveney or the Yare the mouths of which are common, falling into the Rhine at the present centre of the North Sea and thence flowing northward to empty itself into the ocean a good many miles due east of our Yorks sea-board. The Forest Bed extended right down from Cromer along the coast to Kessingland and Southwold, and is the oldest bed of the kind in the neighbourhood ; submerged forests of various ages have been found in the Waveney Valley, but none of them are thought with any degree of certainty to be coeval with the Cromer one. In order to ascertain whether our Valley be a natural basin in the chalk retaining an early river, we must consider that to-day it rises within a few yards of the Little Ouse, which flows in a diametrically opposite direction to the Wash. The sources are separated by a late superficial deposit of fluvio-marine sand and gravel, so that, considering the much further historic expanse of the Wash southward, it were but natural to allow the former unity of these streams. And the cause is not far to seek, for the pull of the chalk crust was from west to east , hence it became broken at right angles, causing such north and south tension as to excavate our Valley in the interim. Sir Charles Lyell reiterated the fact that " not a foot of the land we inhabit but has been repeatedly under the waters of an ocean ; " and, since the chalk era, all East Anglia has time and again been submerged by sea and flood, which spread so thick a coating of later deposits over our Valley as to obscure any chalk-depression that may have existed. Hence the chalk-land that was raised above sea-level, clothed with profuse forest and herbage, and inhabited by animals of which many were pachydermatous, as well as by numerous species of both birds and insects, all gives way to a new phase : from whatever terrestrial cause, it is certain that the whole of our eastern peninsula sank. Fully three-quarters of its surface were again covered by the ocean, probably extending to a point some ten miles west of both Norwich and Diss. These waves for
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ON THE FORMATION OF THE W A V E N E Y
VALLEY.
centuries rolled back and forth chalk that was largelv dissolved in Solution, and out of it washed flints which were of so much harder consistency that no more than their rugosities became eroded by attrition. So great was the scour that beds of these and other stones, at least fifty feet thick, were laid down in process of time ; while others of sand, often beautifully white as that now at Gisleham, and equal density formed in quiet estuaries, where lived and throve millions of mollusca and other classes of lower marine life. Here such lived out their little span and left behind their pearly shells ; to-day nothing is more representative of East Anglia's palaeontology than these masses of the Mammalian Crag of Norfolk and Red Crag of Suffolk, extending in Essex to Walton. Wonderful segregations have been found near Norwich of a stone-bed, resting upon chalk, consisting of large flints mixed with great mammalian bones of Mastodon arvernensis, elephants, horses, stags, beavers, etc., over which is Crag of Norfolk and the other sort from Chillesford in Suffolk, all capped by some five feet of sands and clays. Crag is present upon both sides of the Waveney Valley ; and both Dr. Crowfoot and Mr. Dowson found seventy species of its typical mollusca in the old brick-pit at Aldeby. The bed is pierced whenever deep borings are sunk at Beccles ; and the sandy gravel on the southern side to Bungay is derived from Crag.
T h e V a r i a t i o n of s u c h f o s s i l s d e m o n s t r a t e s t h a t b e f o r e
this period ended our climate had passed from subtropical to temperate, and the latter terminated in arctic conditions approaching those preceding the Great Ice Age. Next the Crag-oceans receded ; again the Waveney's banks were high and dry, covered with oak, yew and alder. Such trees were found in the peat bed at Beccles bridge, at the same time as they were discovered sixty feet below the Waveney at Haddiscoe, containing branches with bones of fossil horses. Than to-day, the Waveney then flowed through a much deeper Channel, rendering its unerosed banks a hundred feet higher. Then all became changed : exceptional cold set in, and Waveney-land with other parts of England lay ice-bound. Glaciers of enormous size rolled down from the northland ; three thousand feet of ice capped the Scottish hills ; moraines ploughed across the North Sea ; and East Anglia was obscured beneath a floe that advanced first from the north and then from the north-west. As the glaciers came across the midlands they gathered masses of the local stones, the tops of limestone hills were torn away, and softer Jurassic and Liassic rocks embedded themselves like putty in the ice. Heat came, all thawed, and such was the volume of foreign matter carried in suspension that Cromer cliff shows sheer forty feet of hard clay all melted from the ice upon that spot alone. Such mud now constitutes
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the top-soil of our land ; and such roaring floods as the great thaw brought wrought havoc upon the river-beds, for both Fritton Lake and Lothing Lake at Lowestoft were nearly surely cut out beside the Waveney at that time. At Beccles we see three glacial periods indicated in the Ingate-road brickyard and in the Weston brickyard : everywhere is scattered the detritus carried here by ice; and I have picked up specimens from Scotland, from Yorks, Derby, Lines., and even far-ofi Scandinavia. The last ten thousand years or so, a period too recent in the lapse of Time to count for much, have seen the sea receding or the land sinking upon various occasions. In no other way can we account for the comparatively late forest beds, which appear at various depths within the estuaries of our country. Evidence of such subsidence emerges in the Waveney and other coastal rivers of both England and Wales ; here are three in the former at Beccles and Haddiscoe, where is the lowest at sixty feet under its present bed, the next at about thirty feet and the top one not far below its present surface. Data are conclusive that variations in land and water levels have taken place, and that the Waveney shared such vicissitudes with other localities. Mr. C. Reid has studied such modifications in relation to submerged forests, and given details from localities around the coast excavated for dock-building. That the water-level of the Waveney Valley was higher some eight hundred years ago than it is now must be obvious to everyone ; Mr. Claude Morley maintains (Proc. Suff. Inst, xviii, 52), from the comparative dip of the Fenland water-mills, that the difference is fully five feet on the west of Suffolk. Certainly in Roman times the Waveney estuary extended to Bungay ; in Norman days Domesday proves by its herring-rent that Beccles overlooked salt-water, which condition of communication lasted tili at least 1200, when Breydon Water silted up. Since then the stream has been shelved and controlled, with the result that very much of its lateral waters have been claimed for riparian cattle-marshes, later valuable grazing-ground. Present changes are restricted to those caused by the elemental influences of frost, rain and wind, that combine to imperceptibly obliterate to a dead level all such ridges and inequalities as time has left for our investigation.