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Hi, 

 

I headed out for a full day of collecting at Hamstead on Saturday, and thought I'd share how it went.

 

I reached the beach at Hamstead Duver around 9am and began searching the foreshore.  The finds on this part of the coast are washed round by longshore drift, but it can be a productive section. This was definitely the case on Saturday, within the first 20 odd metres I picked up various pieces of trionychid carapace, Emys fragments, and the worn trochlea of an anthracothere humerus. I continued west along the coast before reaching the slipway (a disused boat launching ramp, apparently used by the US military in preparation for the Normandy Landings) the point where Hamstead Cliffs begin. Having not been able to visit in nearly a month, and after weeks of pretty violent storms over Christmas and the New Year, the coast at Hamstead Ledge has now completely changed.

 

Most of the sand and gravel has been taken off the beach leaving large exposed areas of Bembridge Marls strata on the foreshore. The junction bed between the underlying Bembridge Limestone and Bembridge Marls is also now visible (usually obscured by sand and gravel). The Bembridge Limestone Fm. lays beneath the Bouldnor Fm. and was laid down in a series of large carbonate lakes on a heavily forested sub-tropical coastal plain stretching across what is now the northern Island. At 34.0 million years ago rising sea levels flooded the plain and the estuary/lagoons of the lower Bembridge Marls were deposited, which can be observed in the low cliff face. 

 

5a605e6ccd648_hamsteadcliffsection.thumb.jpg.d6fb76b70813fa340015c6fade44e3a8.jpg

(A small normal fault can be seen in the Bembridge Marls highlighted in yellow, additionally the 'thin white horizon' is the western limits of the famous Insect Limestone. However it is un-lithified and does not produce insects at this locality)

 

The largest change however was an enormous landslide just west of the ledge in the high cliff face. As well as several smaller falls and slips, this slip has littered the beach with clay debris and small trees. It's on the site of a large mudflow from last winter, I reckon the heavy rain saturated the already weakened area and triggered a large scale failure of the cliff face. I checked through the debris (and the exposed strata) and found some very nice pieces, including a huge piece of trionychid hypoplastron (the largest turtle piece I've ever found), a fragment of alligator jaw, a large fish vertebra, and two large baso-occipital bones from Bowfins (Amia sp.). As the beach was covered with clay blocks the foreshore wasn't very productive for ex-situ finds. 

 

As the tide dropped I moved further west towards Cranmore and beach conditions returned to normal with shingle, sand, and gravel, and a nice variety of finds. The best finds were a couple of anthracothere teeth, including a very nice canine. Coprolites were also very common as usual, most, if not all, are likely crocodilian. Further west there are exposures of the Upper Hamstead Member on the foreshore which if you're lucky turn up in-situ finds. The Upper Hamstead Member dates from approximately 33.2 - 32.4 million years ago. This time I was in luck, I spotted a large bone fragment and a piece of Emys weathering out of the clay. I checked the areas adjacent in case there was anymore associated material but unfortunately not. The bone fragment appears to be a rib. 

 

I reached Cranmore and collected some matrix for micro-sieving from the cliff face, and after collecting a few more bone fragments and coprolites, and with the tide now rising I called it a day and headed up to the main road. Overall it was a good collecting trip, with some good finds. Hopefully as the winter goes on the landslide debris is eroded away and some nice vertebrate remains are produced. 

 

Hope this was interesting, 

 

Theo 

 

1. Huge piece of trionychid hypoplastron

IMG_0311.thumb.jpg.2dea4085d46203ec785b3e63c74348ca.jpg

 

2. 'Interior' view of the hypoplastron 

IMG_0312.thumb.jpg.5747324fa179519fa10e69f9ade5ae8a.jpg

 

 

 

 

 

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Looks like a cool place to collect!

Thanks for the write up. 

Regards,

    Tim    -  VETERAN SHALE SPLITTER

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"In every walk with nature one receives far more than he seeks."

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Very informative and interesting report. 

Enjoyed it very much, thank you. :)

Life's Good!

Tortoise Friend.

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Nice finds! I really must visit that area and collect someday, very interesting place indeed.

“...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin

Happy hunting,

Mason

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Great post, my favourite find is the canine, that's a beauty.

 

Also thanks for the geological boundary photo and picture of the insect horizon, i didn't actually know what it looked like previously (though i've never collected east enough along that coast to see it either). 

 

How large is the hypoplastron? 

"In Africa, one can't help becoming caught up in the spine-chilling excitement of the hunt. Perhaps, it has something to do with a memory of a time gone by, when we were the prey, and our nights were filled with darkness..."

-Eternal Enemies: Lions And Hyenas

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@Paleoworld-101 Cheers! 

 

No worries, this is the very western limit of the horizon but from Hamstead Ledges onwards it thickens and becomes much more lithified, turning from this silty marl into limestone. 

 

It's 8cm across and 8cm down, it's definitely the largest piece of any freshwater turtle I've collected!

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