Great Eastern Pingo Trail

In 1869 trains steamed their way regularly down the 3-mile (4.8km) stretch between Stow Bedon and Great Hockham. The line, known locally as the Crab and Winkle, was particularly busy during the Second World War, when it was used by servicemen from nearby RAF Watton. However, all rolling stock stopped rolling here in 1965 and the line became one of Dr Beeching's casualties when he declared the service uneconomical.

In 1971, the county council bought the land, thinking it would make an excellent route for part of the A1075, but the plans changed and the road was built elsewhere. The council was left with a narrow strip of land that was not particularly useful, but with great foresight and imagination they decided to develop it as a public footpath. All along the first part of the route, you will see reminders of the days when this was busy with trains, with cuttings and embankments and the occasional ruins of a railway employee's cottage shrouded in brambles. The wood and metal bridge across the stream near Thompson Carr has a distinct look of the railway about it, and sturdy sleepers are used to raise the footpath above the marshier segments of the route.

Among the more curious features of the walk are the pingos. These are shallow depressions, often filled with water, that were formed about 20,000 years ago during the last ice age. Bubbles of ice formed underground and expanded, like a large, slippery lens. This lens forced the soil above it up, but years of foul weather washed most of it down the sides, where it formed a rim around the bottom. When the great glaciers finally retreated north, the underground ice bubbles melted, leaving behind small craters - hollow centres with built-up lips around the edges. Some of these filled with water, forming shallow pools that teem with wildlife.

Pingos are common in tundra areas like Greenland and Alaska, but they are less obvious in Britain. At one time there were pingos in a wide band across the whole of the Breckland, but many have been lost through ploughing when the fields were cultivated. Fortunately, the ones around Thompson Water have been left alone and today the area boasts the highest concentration of these unusual features in Breckland.

Near Thompson Water, you will see signs indicating that the land to your left is a military firing range. This is the Stanford Training Area, used for manoeuvres involving about 80,000 soldiers each year. Despite this, the entire area is a Site of Special Scientific Interest (SSSI) and parts of it are untouched, allowing nature a free rein.

Where to eat and drink

The thatched roofed Chequers Inn at Thompson dates from the 17th century and serves a wide range of food. There is also the Dog and Partridge at nearby East Wretham, on the A1075, which serves food and has a pleasant beer garden at the back.

What to look for

On the western side of Thompson Water look for the large slate monument for Norfolk Songline Sculptures on the Peddars Way, with its poem commemorating ancient footpaths and ancestors. The monument is modern and its verse is printed sideways on. Thompson village church is away from the main settlement, suggesting a population shift at some point in its history, perhaps due to plague. College Farm stands on the site of a priests' school that was founded in 1349 by the Shardelowe family.

While you're there

The walk will take you through two Sites of Special Scientific Interest (SSSI): one ranging from Thompson Water right across to Thompson Common, and the other, if you take the extension, at Cranberry Rough. These areas are rich in wildlife and you should look for sedge and reed warblers, yellow iris and marsh fern. The information boards at the sites will give details about what can be seen where and when.