THE LITTLE OUSE RIVER, THE WAVENEY RIVER AND THE BRECKLAND: A JOINT HISTORY

HISTORY OF THE LITTLE OUSE/WAVENEY

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THE LITTLE OUSE RIVER, THE WAVENEY RIVER AND THE BRECKLAND: A JOINT HISTORY R. WEST The Little Ouse and Waveney Rivers form the northern county boundary of Suffolk, apart from a bite taken by Norfolk near Thetford. The river valleys are the site of many nature reserves and areas of natural history interest. These include Redgrave and Lopham Fen with the adjacent valley fens, Hopton Fen, Market Weston Fen, Wortham Ling, Knettishall Heath, and the Breckland areas to the west. It is the geological history of these areas which gives them their natural history interest.

Figure 1. East Anglia, showing the position of Lopham Ford at the source of the Little Ouse and Waveney Rivers.

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Questions arising about their geological nature: Why are there fens along these valleys?

Why are there so many fens in the area where the Little Ouse and the Waveney have their joint source at Lopham Ford, in a flat field within a clear east-west valley at a height of only 25 m O.D., between Redgrave and South Lopham?

Why, at Lopham Ford, does one river flow to The Wash, through the Chalk escarpment between Thetford and Brandon and into the Fenland, while the other flows east to the North Sea (Fig. 1), a truly remarkable situation?

What is the origin of the sand which gives Breckland its character and exceptional flora?

These are questions I have pondered from time to time since I was a research student investigating the interglacial lake sediments at Hoxne, near Diss, in the early 1950s (West 1953). When I retired, while taking a walk at Redgrave and Lopham Fen, these questions came to mind again, and I decided to look into the matter and see what could be discovered. I ended up by walking much of the length of the rivers, more or less from Lopham Ford to Brandon one way, and Lopham Ford to Bungay in the other, a task which I certainly didn’t envisage at the beginning, taking a few years, but greatly enjoyable. To which field experience was added a survey of what had been written on these valleys and the Breckland, and a study of maps, air photos and other publications. The only equipment used was a metre-long soil auger.

Here, then, are my conclusions about the history of the valleys and the origin of the sands of the Breckland; they point to an inter-related history.

The slate of the landscape was swept clean by the ice of the glaciation which advanced across Suffolk from west to east about half-a-million years ago, the ice of the Anglian Glaciation. After the retreat of this ice, a valley system developed which remained the basis for today’s geography, with the Little Ouse and the Waveney each occupying east-west valleys.

During the warm interglacial period which followed the Anglian Glaciation, typified by the lake sediments at Hoxne which overlie the Anglian boulder clay, the watershed between the Waveney and the Little Ouse was not at Lopham Ford as we see it today, but much further east, near Brockdish.

Here the plateau of boulder clay extended across the present Waveney valley to form the watershed between the rivers. The Little Ouse was a major river flowing west towards the Fenland, while the Waveney was a shorter river flowing to the North Sea of the time (Fig. 2A).

Figure 2. Three stages of the evolution of the river system. In A and B the present tributaries are marked by dashes, since some changes of course occurred during the transformation, in both the Waveney and Little Ouse river systems.

A. The development of the valleys after the Anglian Glaciation, but before the later glaciation in the Fenland. The watershed between the Little Ouse and the Waveney is east of Diss, near Brockdish.

B. The formation of the Little Ouse Lake, by blockage by ice near Brandon. With reversal of drainage the lake overflowed into the Waveney valley via the

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Brockdish Channel. The dotted area marks the distribution of sandy sediments in the present headwaters of the Waveney and in the Little Ouse valley to the west, where they are extensively preserved. These sands gave rise to the sand of the Breckland seen today.

C. The present river systems, with the watershed at Lopham Ford.

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The next significant event occurring after this interglacial period was a further glaciation which extended into the Fenland, with ice blocking the valley of the Little Ouse River near Brandon. As a result, water backed up the Little Ouse valley. Water from the Little Ouse and its tributaries (Thet River, The Black Bourn (Ixworth River), Botesdale Brook, Dove River, etc.) combined with water draining from the ice front in the Fenland. This resulted in a linear lake forming in the Little Ouse valley and tributaries, here called the Little Ouse Lake. Eventually, the water overflowed the divide near Brockdish into the Waveney valley of the time, cutting a narrow overflow channel which can be clearly seen between Brockdish and Needham, which I call the Brockdish Channel (Fig. 2B). This short stretch of the valley contrasts with the wider valley to the west towards Diss and east towards Mendham.

While the lake was in existence, it carried sediment from the ice front in the Fenland and sediment from the feeding rivers. This resulted in the wide expanses of sand to the west of the Chalk escarpment around the Fenland margin and in a sand-filled Little Ouse valley. In the valley, the sands reach several metres depth in places. It is this sand that is the source of the Breckland sands we see today. Such a lake west of the Chalk escarpment was suggested by Paterson (1942), a pioneer of East Anglian ice age studies. He suggested the lake reached a height of at least 70 feet (21 m) O.D. There is some evidence for the maximum height of the Little Ouse Lake in the form of shoreline features and sediment variation. It seems to have been around 30 m O.D., giving an indicator of the minimum height of the watershed between the Little Ouse source at Brockdish and the Waveney source. Once the overflow started, rapid down cutting through the boulder clay and underlying sands and gravels in the watershed area took place, and it seems likely that the great widening of the Waveney at Mendham Marshes is a result of rapid erosion of easily-erodable sediments by overflowing waters.

As the overflow continued, the headwaters of the original Waveney were rejuvenated, and erosion in the valley cut back westward, the east-flowing river being strengthened by the capture of the Dove River. In this period, readjustments of the drainage systems took place in the tributaries of the Waveney, including the Dove River (as near Hoxne), Fressingfield Beck and Starston Beck. Eventually, the watershed retreated west to its present position at Lopham Ford (Fig. 2C).

On the melting away of the Fenland ice which blocked the Little Ouse, the river resumed its westward flow to the area of the Wash, with its original headwaters captured by the Waveney. River flow dissected the soft lake sediments. But where the gradient of the lake bed surface was low, preservation of the bed occurred, forming the level sandy flats seen today in the valley upstream from Thetford (Fig. 2B). This is the origin of such places as Wortham Ling (and the old Diss Common), the flat areas at and around Lopham Ford, Knettishall Heath, Rushford Heath, and Barnham Heath. Thus in the Waveney valley west of Diss and in the Little Ouse valley, remnants of the valley fill are preserved. But to the east of Diss, in the Waveney valley, there are low river terraces, formed as the river occupied its westwardextending valley, down-cutting through any sandy infill of the former lake.

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The time since the renewal of the westward course of the Little Ouse (at about 150,000 years ago) covers the last warm interglacial and also the last glaciation, when ice reached the mouth of The Wash at about 20,000 years ago. During this period, the sands of the valley have become widely redistributed by wind action, to give character to the area of Breckland.

There is now the question about the origin of the valley fens. Two factors are involved. The first is water supply: the fens exist where there has been a copious supply of water rising in artesian springs and seepages from the Chalk aquifer underlying the Little Ouse valley and the headwaters of the Waveney.

The second is the localisation of subsidences in the valleys, caused by solution of the underlying Chalk through water movement.

Where the hollows so formed are several metres deep, as at Lopham Little Fen and in the fens to the east (Tallantire 1953, 1969), lakes formed some 10,000 years at the end of the last glaciation and the beginning of the postglacial, which evolved to fens as the sediment in them accumulated.

Elsewhere, as at Hopton Fen and Market Weston Fen, springs are associated with backwearing of the valley sides under cold climate conditions, with the local springs maintaining peat growth in the valley of Hopton Brook. Further small fens occur downstream in the Little Ouse valley, as near Gasthorpe and Barnham Carr, with a similar origin as those upstream, the latter associated clearly with springs.

This brief story of the linked history of the Breckland and the two river valleys is an excellent illustration of the way geology can give a time dimension to natural history. Moreover, it is a dimension which is essential to the understanding of present-day biodiversity.

This investigation would not have been possible without the access to land given me by landowners and farmers in the valleys, and the help given by Dr Helen Smith and her colleagues of the Little Ouse Headwaters Project, Professor Phil Gibbard, the Environment Agency, Forestry Commission, Anglian Water services and the British Geological Survey. To all these, I give sincere thanks. I am hoping to publish much fuller details in due course, but I thought my main conclusions would be of interest to members of the Society, since they so clearly concern the origin of many outstanding sites in Suffolk.

References Paterson, T. T. (1942). Lower Palaeolithic Man in the Cambridge District.

Ph.D. Dissertation, University of Cambridge.

Tallantire, P. A. (1953). Studies in the Post-glacial history of British vegetation. XII. Lopham Little Fen, a Late-glacial site in central East Anglia. Journal of Ecology 41: 361–373.

Tallantire, P. A. (1969). Three more nameless meres from the Ouse-Waveney valley. Trans. Norfolk and Norwich Naturalists’ Society 21: 262–268.

West, R. G. (1953). Quaternary deposits at Hoxne. Trans. Suffolk Nat. Soc. 8: 171–172.

Richard West 3A Woollards Lane Great Shelford Cambridge CB22 5LZ

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