Section 1 Evolution and history Image - Broads Authority 7 Waxham 1.1 Introduction to the evolution NORFOLK R . An Stalham t Hickling of the Broads landscape Smallburgh Hickling R. Broad Bu Barton Turf Horsey re Barton The landscape of the Broads is a product of dramatic e Coltishall Broad rn Winterton-on-Sea landscape change over millennia. Who would have u Neatishead h T How Hill . thought that millions of years ago the area was part of R a warm tropical sea which led to the formation of the Horstead Hoveton Ludham Potter Heigham Chalk strata underlying the area. This is so important to us Martham Horning Wroxham today as it provides an aquifer and has provided building Bure materials, such as lime and flint, a common feature of Marshes Ormesby Wroxham Broad buildings in the area. Cockshoot Malthouse Woodbastwick Ranworth Rollesby Salhouse Sth Walsham Filby Caister-on-Sea Filby South Walsham Upton Stokesby NORWICH R. Bure Thorpe St Andrew Brundall Acle Gardens Brundall Breydon Water Gt YARMOUTH Whitlingham Buckenham Berney Arms Bramerton Rockland Burgh Cantley Rockland R Castle St Mary . Y Claxton ar Reedham e Fritton Chedgrave Fritton Lake R R. St Olaves Chet W a ve Loddon ne Haddiscoe y Somerleyton Burgh St Peter Oulton Broad North LOWESTOFT R.Wave Broads Authority executive area Gillingham n e Oulton y Oulton Broad Geldeston Carlton Broad South approx scale Lock Marshes 0 2 km Shipmeadow Burgh Castle church has one of the characteristic Anglo 0 2 miles Bungay Beccles SUFFOLK Saxon round flint towers. Christopher Hilton 8 © Crown Copyright and database right 2016. Ordnance Survey 100021573. The Broads "A breathing space for the cure of souls" introduction Changes in the relative sea levels saw coastlines The Anglo Saxon period saw settlements established traditional uses decline, economic drivers dictate land advance and retreat and different river systems evolve. that still thrive today, their origins hinted at in their use for agricultural enterprises and conservation bodies During certain periods the Broads was connected to Scandinavian place names. Many of those settlements increase their land ownership. the continent allowing people to travel between the found skirting the Broads area on the higher land have two areas. unusual round-tower churches. When the climate cooled there were periods of glaciation The broads, which give the area its name, were excavated The following sections set out in more detail when ice sheets swept over the area depositing sands in the mediaeval period to provide peat for fuel. The how the physical landscape has evolved over the and gravels which are still exploited today as a source of excavations subsequently flooded providing valuable millennia and what have been the most significant aggregate. areas of conservation and recreational activity today. human actions that have contributed to the character of the Broads landscape today. Ice sheets retreated when the climate warmed and Humans have shaped and exploited the marshland as a the swampy freshwater environment encouraged the valuable grazing resource for many centuries adapting formation of peat an important resource in Broads history to increases in water levels, through the construction and, as we have now come to realise, important as a of flood defences, mill structures and elaborate dyke carbon dioxide store. networks which supplemented the natural creeks in helping to drain the area. The shaping of the Broads by humans to resemble the landscape we see today has only occurred during relative From the 19th century onwards, tourism and recreation recent history. It initially started with the clearance of land activities have had a significant influence on the Broads for grazing but in the Roman period impressive structures landscape. The same can be said of the changing such as Burgh Castle fort were built. management regimes for the wetland landscape as Burgh Castle fort - Two bastions on the east wall. The impressive defences are some of the best preserved in the UK, even Europe. Ashley Dace - geograph.org.uk Dredging and reed cutting are just two examples of how humans have shaped the Broads landscape. 9 The Broads "A breathing space for the cure of souls" Evolution of The Broads 1.1 How the Broads landscape has been shaped over many thousands of years. The physical landscape of the Broads that we see today is the result of many thousands of years of gradual change. Natural land-forming processes, such as glaciation and variation of sea level, work together with climatic processes to bring about a slow but steady transition. The Broads is a low-lying landscape, and so slight shifts in water level and quality may easily have widespread effects. The following text is a simplified version of the sequence of events that have taken place over deep time to shape the physical fabric of the Broads landscape. Some of the land- forming processes are particularly significant today for providing the ‘raw materials’ for the establishment of special wildlife habitat, and for humans to exploit for fuel or building purposes. 10 The Broads "A breathing space for the cure of souls" Evolution of The Broads 70 million years ago This area was part of a warm, tropical sea in the Cretaceous period. Mud rich in fossils and microfossils was deposited on the sea bed, leading to the formation of thick layers of Chalk, which underlies all the Broads area. Underwater scene showing Mosasaurus in a chalk sea. Map of Europe in the Cretaceous period. ©Dr David M. Waterhouse. Image © Prof Ron Blakey, Colorado Plateau Geosystems, Arizona. The Chalk is a vital aquifer for the Broads because it supplies groundwater to the rivers Waveney, Yare and Bure and their tributaries through seeps and 70 to 2.5 million springs in the valleys. It supplies most of the drinking years ago water, directly through boreholes and indirectly from surface sources such as the River Bure at The Broads area underwent Belaugh and the River Waveney at Shipmeadow. Its many dramatic changes, calcareous nature produces lime-rich water, which as seas advanced and influences the distinctive biodiversity of the Broads. Flint is a hard grey rock retreated and climates Flint is a mineral which formed as nodules in the Chalk. consisting of nearly pure silica (chert), occurring changed over millions of It is widely used in the Broads area as a building stone, chiefly as nodules in years. It eventually became whether as cobbles or knapped (broken) pieces. chalk, have been used a lowland area on the edge extensively in local The Chalk can be seen in the Broads area where buildings. of the North Sea basin, to valleys have cut down through younger geological be strongly influenced by layers to expose it. Chalk was quarried and mined Lime workers at any changes of sea level. along the valley sides of the rivers Bure and Yare. Whitlingham Chalk Pit. Image courtesy Whitlingham Trust. 11 The Broads "A breathing space for the cure of souls" Evolution of The Broads The marine sediments of the Norwich Crag 2.5 to 1.8 million years ago Formation are evidence that the Broads 1.8 to 0.5 million years ago The area of what is now the Broads lay area lay under the western North Sea, The Broads area gradually became about 2 million years ago. Three major under the western edge of the North Sea, rivers flowed into the Crag sea, land once again, as local sea-levels in a cool, temperate climate. Relative sea bringing different land-sourced fell and the shoreline of the North Sea sediments to the area. levels were high, and the coastline at that Image with acknowledgments to Lee et al: retreated north-eastwards. The area time lay somewhere near Norwich. Journal of Quaternary Science No.21, 2006. was influenced by two major rivers. Ancaster River Crag North sediments Present day Sea coastline deposited Bytham Bytham Thames River A geological profile through Norwich Crag sediments at Bramerton. The site is conserved as a Site of Special Scientific Interest. Image courtesy Dr Peter Riches. Ancestral River Thames The Bytham and early Thames rivers are thought to have converged in the Broads area about a million years ago, Marine sands, gravels and clays of the Red Crag Ludhamian (about 2.3 million years ago), and Antian with an estuary near Happisburgh.' and Norwich Crag were laid down on the sea floor. and Bramertonian (about 2.0 million years ago ). Image courtesy The British Museum. Sediments of the Norwich Crag are exposed in the The Crag deposits are typically sandy, but sometimes Broads area today, and form areas of sandy soils along contain layers of fossil shells, which may give a chalky the sides of valleys, such as the Ant, Bure and Yare. quality to the groundwater in places. Many mammal Marine sands, gravels and clays of the Wroxham The position of the shoreline shifted as the climate fossils have been found in the Norwich Crag, providing Crag were laid down on the sea floor. They can be fluctuated between a succession of warmer and evidence of life on land and sea at the time, including distinguished from the older Norwich Crag by their cooler periods, leading to deposition of a variety of walrus, whale, mastodon and sabre-tooth cat. higher proportion of of exotic, quartz-rich material estuarine and shallow marine sediments. By analysing As time went on, local sea-levels fell, due to uplift of the they contain. These sediments are exposed in areas the fossil pollen and foraminifera contained in these land. The shoreline generally retreated north-eastwards, of sandy soil along the valley sides of the Yare and sediments, geologists have been able to divide the and a major river (the early Thames) flowed into the Bure.