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From Aug 2006 - Nov 2013 WeDig provided a live forum for diggers & fans of Vindolanda. It has now been mothballed and will be maintained as a live archive.

Here you will find preserved 7 years of conversation, photos, & knowledge about a site many people love. Vindolanda gets under the skin. (Figuratively and literally as a volunteer excavator!) It's a place you remember, filled with people you remember!

Thanks for 7 great years!

Viewing Single Post From: Mike's Geoblog
Mike McGuire
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The decorating work at our house in Derby was completed ahead of time but involved a lot of work and effort on my part moving our belongings from room to room ahead of the painters. So it was a great relief to be back on site at Vindolanda at the start of this week on a beautiful Sunday morning. Since then weíve had quite a lot of rain but some brilliant sunshine as well. Tuesday afternoon I risked a trip up Barcombe Hill and got wet, but a return visit yesterday morning rewarded me with a brilliant view over Vindolanda and the surrounding countryside.

I guess Iím like most geologists in being most interested in the ancient rocks forming the skeleton which underlies the landscape. But looking at the view I realised more strongly than ever the importance of the part which the more recent ice cover has played in determining the shape and texture of the land surface.

For a start, without the erosive power of repeated glaciations during the present ice age much younger rocks would still be at the surface and the present surface rocks would still be deeply buried. And although the harder and softer rock layers do influence the highs and lows of the landscape they are by no means the whole story. Why, for example, is Barcombe Hill there at all? To east and west of it the corresponding strata have all gone. Some quirk of the way the ice flowed must have been responsible, but we may never fully understand what.

After the peak of the glaciation about 20,000 years ago conditions seem to have become slightly less extreme so probably the ice became a bit less thick and flowed a bit more slowly. The iceís erosive power declined and instead of wearing the rocks away it started in places to smear itís burden of eroded material across the landscape as what we call glacial till, a form of boulder clay. Again, although there is some correlation between the landforms and where the till is thickest (generally in the valleys), it is also partly dependent on the vagaries of the ice flow. In some places mounds of till called drumlins were left behind.

After about 15,000 years ago the climate became mild enough that the ice started to melt away. As the ice front retreated past the Vindolanda area, meltwater streams carried huge amounts of water across the landscape, generally southwards towards the South Tyne valley. The force of the water was enough to erode out the small valleys we see today. Mostly it was the boulder clay which was washed away but in some places the streams cut into the underlying rocks creating near-vertical valley sides. Since these meltwaters subsided, there has never again been a sufficient flow to change the shape and size of the valleys significantly. Even flash floods such as the one a couple of years ago, though some big boulders were moved, didnít cause any major erosion.

About 12,500 years ago there was a marked deterioration in the climate which lasted about 1,000 years. The ice didnít return but conditions were freezing for much of the time. Repeated freezing and thawing caused surface rocks to split and was even capable of moving smaller stones gradually downhill in a process with the delightful name of gelifluction. On Thorngrafton Common, behind Barcombe Hill, are a number of lines of boulder scree produced by this process.

Finally the climate warmed again and has remained relatively mild for over 10,000 years. Thick woodland developed over all but the highest ground. However, as settled agriculture started to develop, and particularly as metal tools became available in the bronze age, increasing numbers of trees were cut down to create fields to feed the growing population. When the Romans arrived there was already an established pattern of woods and fields much as there is today, although the proportion of woodland was probably considerably greater. The Romans themselves, of course, contributed to the deforestation and, although there may have been some recovery in the early Middle Ages, recent agricultural practices have reduced the tree cover still further.

So I think the view from Barcombe Hill over Vindolanda has probably changed remarkably little since Roman times. On a fine day itís one of the best views in England. Weíve all seen lots of photographs of it, Iíve contributed a panorama of my own below, but none of them really do it justice. Next time youíre here, and if youíre sufficiently able bodied, do try to make the time to climb the hill to the Long Stone and see for yourself.
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