Constructed by the Saxons over 1200 years ago, the Fleam Dyke is one of Cambridgeshire's most impressive earthworks. (Its neighbour, the Devils Dyke, is the largest monument of its kind in Britain). Today the Fleam Dyke is a ditch and rampart 26m wide and up to 3.5m high, running for 5km from Fulbourn across the dry chalklands to Balsham. In Saxon times it would have been a formidable barrier to movement from the southwest on the ancient Icknield Way. The Fleam Dyke is designated as a Scheduled Ancient Monument and a Site of Special Scientific Interest. Public footpaths allow access to the full length of this peaceful reminder of East-Anglia's war-torn past.
The earthwork and much of the surrounding area was grazed by sheep until the turn of the century. Their constant nibbling kept the grasses short and discouraged the spread of hawthorn and other shrubs. Lack of grazing has allowed scrub to cover the rampart in places, but the Fleam Dyke is still among the best and most extensive areas of species-rich chalk grassland in Cambridgeshire. Unusual mosses can be found in some places. Grassland butterflies and many other insects may also be seen here.
In spring the grassland will be dominated by the blaze of yellow from the cowslips, rockrose, horseshoe vetch and bird's foot trefoil. The early flowering dog violent down the slopes can also be seen at this time of year.
The best chalk grassland flowers come out between June and July and this is when the Dyke is at its most stunning - the mauves and pinks of clustered bellflower, black knapweed, field scabious, harebell, sainfoin and wild thyme are out in bloom across the tops and slopes of the Dyke. You may even see a pyramid orchid!
The display of flowers continues into the autumn with the appearance of milkwort and bastard toadflax in late summer (find out more about bastard toadflax)
We are monitoring the insects and butterflies with the help of volunteers and Butterfly Conservation. The Dyke is an important site for butterflies and from April onwards a variety can be seen including brimstones, small skipper, green hairstreak, painted ladies, Essex skipper, meadow browns and common blues.
Numerous anthills are evidence of large numbers of meadow ants, which are only found in areas of old and undisturbed grassland. The loud whirr of grasshoppers and the humming of bumble bees may be heard in the summer months.
Rabbits, hares and weasels can sometimes be seen, as can the occasional common lizard basking in the sun, or a tiny pygmy shrew scurrying away. There are no bird species confined only to chalk grassland, but there will always be a variety of bird life to give interest, for instance kestrels and skylarks singing overhead, a covey of partridges and, in the woods, summer visitors such as whitethroat and blackcap.
To retain the chalk grassland along the Dyke requires cutting and raking and removing the cut material. The timing has to be carefully planned to allow the flowers time to flourish and spread. The grassland is therefore cut in early spring and late autumn. However last year for the first time in nearly 60 years grazing was re-introduced to on a section of the Dyke, and in 2004 it is planned to increase this area. The sheep used are Norfolk Horn, one of the oldest breeds in Britain. Autumn 2003 saw them introduced to the area south of the A11 towards Bedford Gap. The sheep will graze the grassland but because they are a hardy old breed they also munch on the tougher ranker growth in the ditch bottoms such as elder, privet and young bramble and nettles. If you would like o see the sheep on back on the Dyke why not visit in late April.
Large sections of the Dyke have become scrubbed over and the Cambridge Green Belt Project is working with English Nature and the Friends of Roman Road and Fleam Dyke to tackle this. The scrub is being cut back form the path tops and will eventually be cleared from the bank sides. At the moment this work is concentrating on the areas between the disused railway and Fulbourn. Clearing the scrub will serve two purposes. It helps to retain the chalk grassland flora that has clung on in places and eventually this will hopefully spread down the banks of the Dyke. Scrub roots also threaten the archaeological value of the Dyke and so its removal ill ensure its historical value.
The Friends of Roman Road and Fleam Dyke are a membership group working towards restoring the Fleam Dyke. They complete monitoring work and have occasional work parties. If you would like to become a member and receive the newsletter to update you on all their activities please contact the Cambridge Green Belt Project Officers. The Cambridge Green Belt Project also runs Mid-Week Team work days on the Dyke and regular events.
The Fleam Dyke footpath can be started at either Fulbourn (TL536557) or Balsham (TL579513. There is limited parking at these points. The Dyke crosses the A11 at the half way point where there is limited parking at a lay-by on the southbound carriageway (TL549543). Look at a map