Pingo!
So we set off for a point north of Thetford, where the Peddars Way, a railway bed and some nature reserve trails combined to make a circuit of some 8 or 9 miles. Parked car and off we went. After a while we spotted a waymark that informed us that we were on "The Great Eastern Pingo Trail".
"What's a pingo?" asked Miss W.
"Haven't a clue".
All was revealed as we approached the old station where an information board revealed that the word pingo is derived from the Inuit word for a small hill - except that these hills are ponds. Hundreds of them! So why are they called pingos, and why are water filled craters given a canadian native's name for a hill?

The answer is that they were small hills once - and that was in the Ice Age. Underground springs forced water to the surface, and as it got close to the frozen top soil it formed a lens shaped plug of ice under the soil surface. Over time the partial thaw of summer allowed more water to the top, this froze too and the ice lump got bigger, like a giant blister.
Each summer, when the topsoil thawed, some of it slid down from the top of the dome to the perimeter, forming a circular deposit of debris.
As the climate warmed up and the ice melted, the pingos collapsed to form roughly circular pools with raised edges, which remain to this day. There used to be hundreds more over the Norfolk Brecks, but most have disappeared under the plough as land has been developed for agriculture. Those that remain are a haven for all sorts of wildlife, and as the nature reserves adjoin the 17,000 acres of the army training grounds which have been out of bounds to civilians since WW2 you could say that this area is a truly huge refuge for wildlife.
This is an undemanding ramble, but whether naturalist, geologist or botanist, there is plenty to see. Heathland, woods, wetland, eery tree covered swamps and open meadows. We enjoyed it for its unexpected variety and interest - and its flatness (well, this is Norfolk!).An idea of what the area must have looked like in the ice age is given by the photo opposite, which shows two modern day pingos in the Mackenzie Delta in Canada. The one in the foreground has a ruptured top showing the ice core below. Fascinating eh? Well, I thought so.
More on the breckland pingos from Norfolk Wildlife Trust and the trail details from Norfolk County Council.

1 Comments:
This is brilliant! How interesting. Thanks for this.
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