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Thursday, 4 April 2013

Stripes at Airman's Corner

Thanks to Tony for drawing attention to this "evaluation report" undertaken by Wessex Archaeology.  Full of interesting info!  There are "periglacial stripes" here too -- but they do not show up in all of the photos.  In some of them the chalk surface under the soil appears rather flat, or irregular and lumpy but without clear lineations.  Three of the trenches (6,10 and 11) show things which the authors refer to as "post-glacial stripes" or as "periglacial striping" -- although there is no rationale given for the use of these terms -- and no discussion of what the responsible processes might have been......

 For what it's worth, Airman's Corner sits in a slight dip, and it appears that the stripes seen in the photos run more or less directly down the gentle gradients involved -- ie perpendicular to the contours.

Archaeological Evaluation Report
Prepared for
Chris Blandford Associates
on behalf of
English Heritage

Wessex Archaeology

The fieldwork was undertaken by Steve Thompson assisted by Bob Davis, Dave Reay,
Catrin Matthews, Dave Murdie, Anne Connors, Simon Flaherty, Jonathan Kaines,
Christo Nicolle, Tomasz Wisniewski, Blanka Zohorjanova, Chris Johnson and Ken
This report was compiled by Steve Thompson with specialists report by Lorraine
Mepham (Finds), Pippa Bradley (Flint), Sarah F. Wyles, (Environmental). The
environmental samples were processed by Nicki Mulhall and Marta Perez-Fernandez.
The report illustrations were produced by Kenneth Lymer.
Discussions with Dave Norcott (Wessex Archaeology Geoarchaeologist) and Ben
Urmston (Wessex Archaeology Terrestrial Geophysicist) are incorporated into the
report text. 


Constantinos Ragazas said...


I suppose you can make the argument 'stripes' can exist elsewhere. And that may support your point the Avenue 'stripes' were not all that unusual. And so cannot be the reason for Stonehenge being where Stonehenge is. I agree with you on that.

In my view, the more interesting question is whether or not the Avenue otherwise stands out as a unique natural feature in the subsurface landscape. That would be very significant. Both for MPP's argument as well as my hypothesis.

Two things would make the Avenue stand out. 1) If the 'stripes' run more or less the length of the straight segment of the Avenue. 2) If the subsurface landscape left and right of the Avenue is markedly different.


Anonymous said...

'periglacial stripes' really!!

Of 52 trenches and 43 test pits in close approximation on 5 sites - we are lead to believe that just 29 evaluation plots have so called periglacial stripes(PS).

If we plot these PS's on the map provided on the report we find on area AW only one 1x1m test pit (57) has these features but the three 30x3m trenches that surround TP57 have none - yet the trench to the south (TR5) past the two empty trenches (TR3 & TR4) does have them?

Next door on area AE nine areas with nothing and only one (TR8) has PS's.

In area D we do get a few hits eight out of twenty-one plots which look like a NW - SE alignment (which is strange as next door in Area C the reports state that the stripes go North to South).

Area E has the most PS's thirteen out of nineteen plots - sadly these can not go either N - S nor NW - SE as empty trenches (TR34,TR35, TR42, TR43, TR49, TR51 & TR52) lack any PS's - so this must be East to West, if these so called 'archaeologists' are to be believed.

In conclusion, PS's are either:

1) Tiny weeny little things covering a few feet only

2) PS's (like moles) disappear underground to reappear elsewhere?

3) Or these are medieval or modern plough or cart marks and the so called 'experts' really don't have a clue?

BRIAN JOHN said...

Anon -- your point being........??

chris johnson said...

"Numerous linear and curvilinear trends may be of anthropogenic origin"

Weathered chalk......

Nasca anybody?

BRIAN JOHN said...

Chris -- those anthropogenic" lines and curves are pretty obvious as compared with the "natural" features which tend to be much more irregular if not actually wobbly!

Anonymous said...

Sorry Brian did I lose you in the depth of argument?

These can not be periglacial stripes as they do not have a common direction.

As shown in the pictures in your blog:

BRIAN JOHN said...

No Robert, you lost me in the shallowness of your argument. I had forgotten that you have written your own geomorphology text book which works to a different set of physical laws from all the others. Oh dear -- since when did periglacial stripes all have a common direction? I have seen rather a lot of them in my time, and they can run in any direction which happens to be convenient.

Anonymous said...

"Oh dear -- since when did periglacial stripes all have a common direction?"

According to this self proclaimed 'expert' usually running down a hill!

"What fascinates me about this info kindly provided by Mike is that the grooves run DIAGONALLY down slope. If that is the case they cannot, I think, be periglacial in origin, since all of the periglacial stripes I have ever seen run directly down a slope on the maximum gradient."

Strangely, these 'periglacial stripes' do not match the gradient either - but what do I know?

BRIAN JOHN said...

Anon -- you must learn to express yourself more clearly. Periglacial stripes -- or water-worn rills for that matter -- tend to run directly downslope, however that slope may be oriented. That means they have many directions, not a common one.

The stripes I have illustrated do tend to be discontinuous, and the gentler the gradient is, the greater the tendency to weave about. Why do some of these stripes appear to run diagonally downslope rather than directly downslope? That is exactly what I have been pondering on, with some use of the laws of physics.

Constantinos Ragazas said...

Brian you write,

“Why do some of these stripes appear to run diagonally downslope rather than directly downslope?”

I think we can all agree this is the crux of our controversy. The laws of physics would require some “structural control” of the water flow creating these stripes.

Whereas you believe that “structural control” is due to “subterranean bedding” of the chalk; I argue such “structural control” had to be on the SURFACE of the chalk and likely due to ice embankments restricting the water flow in some direction.

Can we now address this central difference between our views with evidence and arguments pro and con? I have already offered some 'facts on the ground' visible in the aerial color photo of the Avenue stripes. What is your evidence for “subterranean bedding” control of the water flow? Can such be even possible for chalk? Wont the water flow, seeking the fastest way downslope, wash away any such obstructing chalk layers and smooth these out level with the landscape?


Timothy Daw said...

You might like a picture of periglacial stripes at Avebury -
All the best Tim