Stonehenge Bottom and Stonehenge -- from Evironment Agency and
EH imagery, with thanks
But the reference to "glacial till" seems to be more considered.........
Check out this very interesting post:
https://www.buystonehenge.com/the-glacial-a303/
From Steve Hooker's blog site:
Sample 51138, forty litres of the Trench 511 sequence, sits in the Wessex Archaeology archive. Nobody has examined it with the drift question in mind. Clast lithology, fabric, micromorphology and mineral provenance could tell till from solifluction from riverwash. Dating it is a separate fight.
The Wessex Archaeology sample 51138 clearly needs to be looked at by somebody who knows what a till looks like when fresh, and what it might look like when thoroughly degraded.
From Steve Hooker's blog site:
Sample 51138, forty litres of the Trench 511 sequence, sits in the Wessex Archaeology archive. Nobody has examined it with the drift question in mind. Clast lithology, fabric, micromorphology and mineral provenance could tell till from solifluction from riverwash. Dating it is a separate fight.
The four Phase 7B OSL cores: where are the results? If ages exist, publish them. If the cores were never run, they may yet be datable. An age alone would not identify a till, but a Middle Pleistocene number under that coombe would change the conversation.
The hummocky belt at Stonehenge Bottom has never been archaeologically sectioned. One trench through the toe would separate phosphate diggings from solifluction from anything older. I’ll guess permission from English Heritage is a hard ask.
Nobody has clast-counted the coombe and colluvial deposits for exotics. The quartzite at STP72602 says the method can detect them.
Are you the hero?
Anyone could do most of this: no research council, no grant. An afternoon in an archive. A phone call to Wessex Archaeology asking after sample 51138. An email to the Gloucestershire lab asking where four sealed cores went. The trench is the exception. That needs consents stacked three deep, this being the middle of a World Heritage Site, so bring patience and a professional dig team. The documents have been public for years, the samples are on shelves, and the question has never been asked of the material that could answer it. So I hope some fascinated party asks. Maybe that is you, dear interested reader, who made it this far.
Anyone could do most of this: no research council, no grant. An afternoon in an archive. A phone call to Wessex Archaeology asking after sample 51138. An email to the Gloucestershire lab asking where four sealed cores went. The trench is the exception. That needs consents stacked three deep, this being the middle of a World Heritage Site, so bring patience and a professional dig team. The documents have been public for years, the samples are on shelves, and the question has never been asked of the material that could answer it. So I hope some fascinated party asks. Maybe that is you, dear interested reader, who made it this far.
Thanks, Brian. I wouldn’t know a glacial till if I sprinkled it on my porridge, but I imagine sample 51138 is in a blue plastic barrel, if that helps :-)
ReplyDeleteWhen you say “fresh”, do you mean freshly out of the ground, or freshly deposited by the ice? And what might still distinguish a thoroughly degraded till from something that was never till in the first place—after, say, 450,000 years on chalk?
Not easy, Steve. There are many types of fresh till (lodgement till, ablation till, flowtill etc) and recognizing a rearranged or degraded till is not easy since you don't know what it looked like originally! I have a few exposures of till in West Wales that I think are very old -- one characteristic is that they are cemented by either calcium carbonate cement or iron / manganese oxide cement, but one has to be carefuil because cementing can occur in quite recent deposits if groundwater conditions are right. There might be flow structures in a redeposited till, or it might be churned by permafrost conditions over a long period, or the stone-supporting matrix might chave been reduced volumetrucally by solution processes, or clasts might vhave been rotted or physically broken up by freeze-thaw. In other words, difficult but not impossible!
ReplyDeleteBrian, a correction to the passage you quoted. I had read two rows of the Trench 511 context table as one. The "glacial till" wording belongs to context 51132; sample 51138 came from 51135, the light green sand next door. And of the forty litres, thirty-eight went through flotation, with everything above 4 mm sorted, weighed and discarded. So no barrel of till on a shelf, whatever my porridge said. The dated correction is at https://www.buystonehenge.com/the-glacial-a303/#correction-2026-09-08 and your reply prompted a second post on why a washed sample could never pass your test anyway: https://www.buystonehenge.com/stonehenge-glacial-till/
ReplyDeleteWe'd really need a new trench - an in context slice. And there would likely be a better spot than where a road may have sat.
One more thing, and it is aimed at anyone reading this who is closer to the subject than I am. Two cheap moves are sitting there, and they are not mine to make.
ReplyDeleteFirst: a phone call to Wessex Archaeology asking what survives of sample 51138, Trench 511, A303 Eastern Portal evaluation (their Report 5, TR010025-000584). Flot, residue, anything above 4 mm, and whether the context sheet for 51132, the one with the "glacial till" wording, says more than the summary table.
Second: an email to the University of Gloucestershire luminescence lab asking what became of four sealed OSL cores drilled for the same scheme in 2021, STP70501, STP70503, STP70404 and DTP70704 (schedule at TR010025-002259, p12). Two of them sit within ninety metres of the BH5 buried soil. No results appear in any of the 43 public documents. Either there are ages nobody published, or four cores still in their liners, or nothing. One email settles which.
I am an artist with a print run to get out. If one of you asks either question, I would be glad to hear the answer.
Brian, feel free to lift this into a post if it is more use there.