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View Full Version : Odd Usselo Horizon


Andre
Jun8-11, 03:49 AM
The Usselo horizon is a well known dark sandy or peat layer extending from west to central Europe. It's from Allerod age and it's described well here (http://dare.uva.nl/document/125548) by some leading Dutch researchers. Unfortunately the nestor of Dutch Palaeobotany and Palynology reseach (Palaeobotany and Palynology) -specialist on the Usselo horizon - diseased last year.

Anyway, so we went on expedition to a well known moor, hunting for the Usselo horizon and we found this:

http://i55.tinypic.com/vndv1g.jpg

This was one of the last pictures taken -after sampling- but with the camera exactly horizontal so that the inclination can be measured accurately.

http://i56.tinypic.com/egvl88.jpg

The layer is about 60 mm thick at the highest point but only 20mm at the lowest point. Detail here:

http://i54.tinypic.com/zo73ie.jpg

The layers are predominantly sandy but more dense, likely mixed with clay (loam) (http://en.wikipedia.org/wiki/Loam). The nature of the dark brown color is unclear at the moment.

Anyway the usselo horizon is usually horizontal obviously and not layered (stratified), so what is it?

Nik_2213
Jun8-11, 11:14 AM
Is that dune-sand, so aeolian ??

Andre
Jun8-11, 12:12 PM
River sand actually; mostly delivered by the Rhine river towards the delta of the low countries where it became aeolian. The Usselo Horizon splits up the "younger cover sand I" and II. See this (http://books.google.nl/books?id=LpIPVaQwC4UC&pg=PA143&lpg=PA143&dq=usselo+younger+cover+sand+I&source=bl&ots=BpL8i2Qwri&sig=GEHoca5fwqFDKKaNWsVgCgfDxSA&hl=nl&ei=zqvvTYfGBM2aOpuRjN4B&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDEQ6AEwAg#v=onepage&q=usselo%20younger%20cover%20sand%20I&f=false)

Note that the younger cover sand I below the Usselo horzion is slightly paler in color. That can also be seen here, about 100 feet from that location, showing the horizon more typically.

http://i52.tinypic.com/9ptizt.jpg

But also here, and this site is about 100 miles to the north

http://i52.tinypic.com/2encokx.jpg

NileQueen
Jun18-11, 09:41 AM
Another source area for the coversands besides the Rhine Meuse, is the basin of the North Sea before it infilled.