Impressive bedding

The current exposure at Exeter. Beautiful cross bed sets, but beginning to get overtaken by vegetation.

I realised this morning that I never got around to posting this up.  While showing the new undergraduates a bit of Devon geology last month, we took them to an exposure of aeolian cross bedding which has been used by the department for years.  For an explanation of dune cross bedding, Wikipedia actually does a pretty good job, with the assistance of a decent animation.

The exposure is at the gates of a quarry, and over the years has gradually become more and more covered by vegetation.  We thought it might be an idea to have a scout around the back towards where a new retail park had been cut into the hillside to see if any new exposures had been created.

Sure enough, behind Toys ‘R’ Us we found what will in the future be quite a nice long exposure of dune sets, although not demonstrating the cross cutting sets very well.  We took the undergrads down to show them.  It also provided an opportunity for this photo. Unsurprisingly we drew some very strange looks from customers.

The real gem, however, was to be found from standing in a patch of nettles on top of a rubbly pile, next to a busy main road, peering through some security fencing.  This is basically the rear of the exposure we normally look at, within the quarry. This astonishing exposure makes me wonder what geology was destroyed by these excavations. A single dune set filling the vast majority of a 12m cliff face.  For the geologists among you I would be genuinely interested to hear if you have you ever seen many individual cross bedding sets this thick?


About Pete Rowley

Earth Scientist with a background in volcanology and sedimentology. Enjoys a good rant, beer, and games. Dislikes reality TV, crowds, and unreasonable people.
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3 Responses to Impressive bedding

  1. Pete says:

    I think there are many examples bigger than this in the various Permian, Triassic and Jurassic aeolian sandstone units of Utah and Arizona – see for example Doe and Dott 1980, JSR who document cross sets in the Pliensbachian Navajo SST up to around 30m thick . Everything is bigger in America 😉

  2. geologygeek says:

    So I’ve heard! I had a feeling that would be the case.

  3. Becky says:

    I am having flashbacks looking at these photgraphs! Repressed memories of first year fieldtrips…

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