The Levels are also rich in earthworks preserving elements of the medieval and later landscape. These include several moated farmsteads (e.g. area 8), sea and reen-side banks and surface ridging in fields created to improve drainage. Slight earthworks, such as those in the last category, are very fragile and can be destroyed in a single ploughing.

The Levels are also important for their very high yielding pasture, and large areas are classified as grade 3b agricultural land. As an open space close to major conurbations, they provide an under-exploited recreational resource.

A detailed history of the Gwent Levels is described in the book "The Gwent Levels - The Evolution of a Wetland Landscape" (Rippon 1996). What follows is a basic summary based upon that work.

The Gwent Levels consist of up to c.10m of alluvium and peat, stratified within which there are abundant traces of man's exploitation of that wetland environment during the prehistoric period onwards. Particularly rich are the peat deposits, which preserve wooden structures as well as a record of the changing environment covering many thousands of years. Recent years has shown that entire prehistoric landscapes lie buried in the Levels.

The distribution of major archaeological discoveries shows a marked bias towards the intertidal zone, since this is where the alluvium that overlies the prehistoric and Roman landscapes has been eroded away. Like the peat layer itself, this density of archaeological sites is likely to continue inland, but simply lie undiscovered. Another concentration of sites lies along the fen-edge, where there has been considerable development exposing the archaeological remains.

Mesolithic human footprints and camp sites, and well-preserved wooden Bronze Age/lron Age houses and trackways, have all been discovered through careful archaeological excavation (eg area 6).

At the end of the Iron Age (c.2,000 years ago), the Gwent Levels were a tidally inundated saltmarsh.

During the Roman period, (c.l,750 years ago) the legionaries based at Caerleon enclosed the Levels with a sea wall, so preventing further inundation. They drained the land with ditches and probably used the rich meadow land to graze their cavalry horses, (suggested by the high proportion of horse bones from excavations of a Roman settlement at Rumney Great Wharf). An extensive part of that Roman landscape is still in use around Peterstone (character areas 16 and 17) and is a unique survival in Britain if not north-west Europe.

However, during the post-Roman period, (c.1530 years ago) the sea defences failed, and parts of Wentlooge along with the whole of Caldicot once again became a saltmarsh, with the Roman ground surface buried by alluvium.

The area was recolonised after the Anglo-Norman conquest in the late eleventh century. During this high medieval period (c.1070-c.1350), sea walls were rebuilt and a new drainage system established. The position of the original wall is not known, because of later erosion. Where the Roman landscape survived, it simply needed restoration and rehabilitation. Over many centuries, a new network of drainage ditches was dug, until the present pattern finally took shape; the last major period of landscape creation was in the mid nineteenth century, when new fields in the Broadmead area of Redwick and Caldicot Moor were laid out.

Settlements concentrated on the higher coastal land, surrounded by their arable and meadow fields. The Priory at Goldcliff was particularly important in creating the landscapes of Nash, Goldcliff and possibly Whitson and Porton (areas 1, 3 and 4).

Some fields created during this period were enclosed by ditches, as we see today. Other medieval fields were "open", with only slight grassy banks separating the strips of land (depicted on early maps such as those of the Commissioners of Sewers 1830/1831; GCRO D.1365/2). These strips were allocated to the villagers annually, but in the winter all their livestock was free to graze off the "open fields", unimpeded by fences, hedges or ditches.

The lower-lying back-fen was open common pasture, which lacked drainage and so was only available for grazing during the summer months (eg. area 9). Such areas were known as "moors". Over time, as population increased, parts of the open back-fen commons were enclosed and drained (eg area 9). Tintern Abbey had been granted extensive estates in these areas and was one of the great "improvers" (areas 8 and 10).

During the late medieval period (c.1350-c.1536), there was great social unrest, while plague led to a population decline. A climatic deterioration resulted in coastal erosion. Around the fifteenth century, the sea wall had to be set back, an early example of "managed retreat". Evidence for this can be seen all along the coast, as the sea wall cuts diagonally across earlier fields (eg. area 4); in places the lines of existing field ditches inland of the sea wall can be traced into the modern intertidal zone.

Much of the Levels were divided into fields by the early fourteenth century, but the last areas of common land were only enclosed, through Act of parliament, in the mid nineteenth century (eg Caldicot Moor, area 11). In the preceding centuries many of the "open fields" had also been enclosed, though the greatest of them, Redwick's "Broadmead", was only extinguished in 1850, again by Act of Parliament (area 7). Areas of saltmarsh that had built up around the mouths of the major tidal rivers were also reclaimed at this time.

The former can be termed "irregular", and are of great complexity (eg character areas 1, 6, 15 and 18). They have small irregularly shaped fields, often incorporating the meandering lines of former tidal creeks. A piecemeal process of landscape formation occurred, in the eleventh to fourteenth centuries ("high medieval" period). Roads are sinuous and broad, often with an abundance of roadside waste; these "droveways" were vital for moving livestock from summer to winter pastures. Settlement was dispersed, with hamlets, isolated farmsteads and cottages scattered throughout the landscape. There were a number of commons that became the focus for settlements eg Broadstreet in Nash; Whitson; and Peterstone).

Colonisation started on the higher ground towards the coast. The lower-lying "back-fen" was only drained later, as population rose, increasing the demand for land. A sequence of reclamations can often be identified, as communities gradually drained the back-fen. These areas tend to have landscapes of an "intermediate" nature; rather more regular in lay-out than the "irregular landscapes", but not so rigidly planned as the "regular" variety. Intermediate areas are characterised by a fairly rectilinear pattern of fields and roads, with just the occasional farmstead or cottage.

The "regular" landscapes are very different. Their fields are rectangular and occur in large blocks of similar sized fields (eg areas 11 and 21). The roads are straight and narrow, lacking roadside waste. There is very little settlement, mainly as these landscapes occupy be lowest-lying land. A very different process of reclamation was responsible for their creation; the large-scale and rapid enclosure of extensive tracts of land, in a single episode.

The Gwent Levels comprise c.111.2 km2 of reclaimed estuarine alluvium between the Rivers Ely and Wye in southeast Wales, collectively known as the Gwent Levels. Together, they form a coastal plain up to 6 km wide, fringing the northern side of the Severn Estuary.

The two largest levels are Wentlooge, between the Rivers Rhymney and Ebbw, and Caldicot between the River Usk and the bedrock promontory at Sudbrook. Smaller areas of alluvium are Cardiff West, Leckwith and Penarth Moors between the Taff and Ely; Cardiff East and Pengam Moors between the Rhymney and Taff; the Level of Mendalgief between the Ebbw and Usk; and St Pierre and Mathern Levels lying between Sudbrook and the River Wye.

The Levels have been totally hand-crafted by man. They were created through the enclosing and draining of tidal saltmarshes, and are still dominated by the need to manage water. Without sea walls, all the Levels would be frequently inundated by the sea.

Another constant problem is managing rainfall and run-off from the uplands, which is dealt with by a complex system of channels that carry water off the surface of fields ("ridge and vurrow"), into large gullies ("grips") and into the network of field ditches. Water then drains from these into major watercourses known as "reens". This network is the key feature of the Levels, both in terms of their ecological importance and the historic landscape.

The method of drainage was first established in the Levels nearly 1800 years ago. It takes the form of a hierarchy of drainage channels, which also provide a basis for the historic and nature conservation importance of this area.

The maintenance of this system has always been a co-operative effort by farmers and the authorities in power. The former have tried to protect their livelihoods and prevent fertile lands being destroyed by flood. The latter, beginning with the Roman legions and continuing with the medieval monasteries, marcher lords, the Commissioners of Sewers, and a range of modern bodies, have been seeking to preserve their interests in, and responsibilities for, the Levels as a whole.

The whole drainage system in the Levels relies upon the sea wall. Historically the wall has retreated, with much of its present line dating from the late medieval period. In a total length of c.35 km, there are many different styles and dates of wall which were steadily improved and modified between 1954 and 1974.

However, following a heavy storm in 1990, these sea defences were tested to the extreme and the NRA are proposing a 10 year programme of raising and strengthening the wall. This may produce a much more standardised structure hiding the existing complexities.

The proposed works make the short lengths of relict sea wall at Rumney Great Wharf, Peterstone Gout and alongside Collister Pill even more valuable.

The saltmarsh beyond the sea wall has traditionally provided summer grazing. Only two farmers continue this practice on the Wenthooge Level but it assists in maintaining the diversity of the plant communities.

The NRA are also responsible for the rivers which divide up the Gwent Levels, and the management of c.64 km of main reens in which upland streams have been canalised to run across the low-lying levels and out through tidal flaps (gouts) to the sea.

Some of these main reens, such as Monksditch and Mill Reen, flow between raised banks onto which the periodic clearings of the reens are dumped. These earthworks are also major historic features within the landscape, which should not be unnecessarily damaged. In places (eg Monksditch near Whitson sub-station and the north end of Blackwall in Magor), the reen sides are revetted by stone walls and timber facings, which should also be retained.

The next tier in the hierarchy of drainage channels are the c.137 km of reens managed by the Caldicot and Wentlooge Levels Internal Drainage Board (IDB). These provide the boundaries and framework for most of the character areas defined in this report.

The continued management of this system is assured, but several types of historic features occur within this network and need protection. Water levels are managed in these reens by pens known as "stanks", in which wooden planks can be set to raise the water levels in summer and reduce them in winter. These structures, now in brick and concrete, remain an important feature of the Levels and need to be properly maintained.

Another important feature, unfortunately now very rare, are "walls" which seem to have been low earth banks built on the uphill or seaward side of those reens dug to drain the back-fen. They provided additional protection from winter flooding to the better land behind.

Another feature of these main reens are the lines of pollarded willows planted to strengthen the bank sides. These are an important part of the historic landscape as well as of great ecological importance.

By far the largest tier in the drainage hierarchy is the c.1200 km of field ditches maintained by the individual landowners. Here, the clearance of ditches and management of the associated hedges may extend over a 10 to 30 year cycle.

These boundaries are much more vulnerable to loss as larger fields are created from several smaller ones. In the remaining agricultural areas of the Caldicot Level, 18% of the boundaries that existed during 1886 have been lost while in the Wentlooge Level the figure is 40%. Hedgerows constitute a significant component of the landscape character of the Levels. The way that hedgerows are managed will significantly affect the visual appearance of an area as well as influencing the nature conservation interest. For example, in the lowest-lying back-fens (e.g. areas 9, 20 and 21), fields tend not to be hedged being characterised by stands of reeds and isolated willows.

Part of the character of each landscape area is provided by standing buildings. The dispersed settlement of isolated farms in the coastal parts of Wentlooge and western Caldicot (all "irregular landscapes"), contrasts with the nucleated village of Redwick in eastern Caldicot (area 5) and linear settlement along Whitson Common (area 3). The back-fens are largely devoid of settlements ("intermediate" and "regular" landscapes), though the fen-edge has always been a favoured location for occupation.

The farm houses and farm buildings have always been at the centre of the area's economy, but they are threatened as landholdings are combined. In some cases, farm complexes have been abandoned by new institutional owners.

A review of the list of historic buildings for the Gwent Levels parishes, currently being undertaken by Cadw, will highlight and protect those of special interest. The character of the Levels will be maintained only if traditional buildings are retained in use.

Alongside most farms used to be an orchard, and the surviving examples are an important feature of the Levels. The end of cider making locally means that most orchards are no longer commercially viable. However, there are some fine examples, notably in Goldcliff, Redwick and Magor