Help With Explaining a Fill

[angi]

Hello all. T'other half is too lazy to create a new profile, so I am posting this question on his behalf. Can anyone offer their opinion? Ta muchly! :

"I have been excavating a Romano- British feature these past few days. It is sub-circular, roughly 8 metres across, 1.2 metres deep, fairly steep sides which drop to vertical followed by a flat base.

The initial few fills are slumps of natural sand and gravel with little silt. Then the whole lot is covered by a layer of sand and gravel which has been cemented by what appears to be iron, so that the fill is very solid and compact. The fill also contains lumps of iron stone.
The fills above this change to dark silty clays containing domestic animal bones.
The gravel fills have very little in the way of finds.

What sort of a depositional environment would result in the gravel becoming cemented with iron? Is this a sign of waterlogging but free from vegetational and organic decay?
My current best guess is that the feature was kept full of water and was kept clean and free from decaying plant matter which is why there is little silt and few finds, and that the silts and clays represent the abandonment of the feature and it becoming gradually filled by vegetation and rubbish."

[trowelmonkey]

"Ferrugination: (L: ferro= iron; ferruginis= rust) iron sesquioxides adhere firmly to sand and gravel, giving them a red colour, and may cement them to form a subsurface iron pan." Iron pans form in a few ways and since I'm not a soil scientist I'm not going to try to describe them.

The iron panning you described would have occured after the dark silty clay fills were deposited in the cut feature. Iron panning commonly occurs at an interface between ferrous and non-ferous deposits (not getting into the sediments vs soils debate here)that are quite damp. This phenomenom is fairly common in ditches in some parts of the country.

The important thing to remember in archaeology is that iron panning is frequently an indicator of a high level of cess in one of the deposits. The clay-like nature of the upper deposit seems a good indication of this. (Does it feel soapy and is there a slight gloss to it?)

Ironically, although water passing through the deposits creates the iron pan in the first place as it accretes it becomes more difficult for the water to pass through and the above deposit frequently becomes water-logged. That's one of the reasons raised bogs are wet. (I hope your other half got lots of samples from the dark deposits.)

Physically the iron pan deposit belongs to the redeposited natural series, sequentially it comes at least after the initial dark deposit above it. Oh, how I love matrices!

I'm not going to hazard a guess as to what the feature is without knowing what's nearby. Hope this helps.

[BAJR Host]

A better description cannot be made... (well... not by me anyway!) good clear answer.. I understand it myself now.

"I don't have an archaeological imagination.."
Borekickers

[angi]

Thanks for this! I just have to try to figure out how to text it to him on site :face-approve:

[trowelmonkey]

Glad to be of service. That's what I love about archaeology, there's always someone around who knows something. I guess that's why it's so egalitarian. Me, I'm rubbish with bones (think small, medium or large quadruped), but - donning battered indiana Jones style hat - I give good strat

[BAJR Host]

you certainly do!

And you are right. I remember one site in particular (Kellington) where everyone was an expert in something.. boy did I learn loads on that site... I may have gone mad.... but I learned a lot.

thanks trowel.

I wonder if I should reorganise the forums a bit... and have a questions section... whats this pot... has anyone seen such a weird cut etc...

"I don't have an archaeological imagination.."
Borekickers

[Kel]

quote:I just have to try to figure out how to text it to him on site

How about:

OMG!! Ugot Poo! Were Marigolds- Srsly! LOLZ kthxbye

(Trying to get the hang of this yoof stuff before starting uni next month. Not sure if it's working...)

[angi]

quote:Originally posted by Kel

quote:I just have to try to figure out how to text it to him on site

How about:

OMG!! Ugot Poo! Were Marigolds- Srsly! LOLZ kthxbye

(Trying to get the hang of this yoof stuff before starting uni next month. Not sure if it's working...)

heh heh! I shall try that [:p]

[trowelmonkey]

quote:Originally posted by BAJR Host

I wonder if I should reorganise the forums a bit... and have a questions section... whats this pot... has anyone seen such a weird cut etc...

"I don't have an archaeological imagination.."
Borekickers

Sorry for the long posting, too much caffeine.

Questions already turn up here from time to time and sometimes get answered (sorry, long time lurker), so a forum to gather them seems really useful. Almost everybody I know informally sends photos around when they’re stumped since that’s often the best way to get a point across. Since BAJR is in the public domain this though could have real copyright and client confidentiality issues. Personally, I don’t see a problem with tight shots that don’t give away any extraneous detail, but who would filter them? How do the managers out there feel about this?

May I be audaciously bold and suggest something even more ambitious?

Like many people on this forum I started digging before I went to uni. I went to uni because I naively thought I would learn how sites were formed and how to recognise stuff. This was the last thing we learnt. I remember a slide of an in-filled ditch and a cropmark and that’s about it. Don’t get me wrong, I learned a lot of new things, but NOT about digging. These days most new diggers don’t seem to have so much experience of even seeing features, a real shame.

Ever so often I have mooted the idea of a book describing typically encountered British archaeological features because I have yet to see a single anything address this in an easily accessible way. Something like the back bit of The Handbook of British Archaeology expanded. I have always been told that this is both unnecessary and impossible since each feature is inherently unique. Yes, I’ve said, this may be so, but surely there is a reason why we recognise a posthole or a cooking pit when we see one. Why is one blobby hole a quarry and another a tree bowl? One has to wade through so much disparate literature to get an idea of how features form and how they behave after that-. Some sources are great for what they do but are limited in scope, such as Carver’s Underneath English Towns. And yet those good sources tend to have mostly nice, crisp line-drawings, very clear for the theory, but what the beginner of any new geology needs are nice, clear photos.

I think many of us have had the less than great experience of starting somewhere new and being sent off on a watching brief straight away with no one to ask what’s normal. Worse yet in the last few years, the big site where there aren’t enough old hands around and the harassed supervisor/PO says “that’s not a posthole, it’s just a pit!” “Why?” quoth the newly graduated with two weeks experience desperate to find something. “Because it isn’t, now get on with it there’s an area to hoe back,” growls the harassed super/PO. (Okay, so I exaggerate a little for wooden dramatic effect, but you know it happens.)

I still think a little guide would be very useful but have come to think that the internet is a much better tool to disseminate this kind of information. Is anybody (bajr?) interested in hosting something like this?

I was inspired by these sites: http://www.wossac.com/projects/photography.cfm and http://eusoils.jrc.ec.europa.eu/projects...cfm?myID=0

This would be my wish list:

It ought to be searchable by geology or type, so either “postholes” or “boulder clay”

Common Features:
Postholes; hearths; kilns; furnaces, different types of “natural” which has been exposed to heat; ard marks; storage pits; quarries and the like.

Juicy, slightly complicated things and an explanation why:
Inverted stratigraphy, for example caused by land slip; re-cut ditches (with clearly separate phasing) vs ditches that have been re-dug within their use-life; buried banks; robbed out walls.

Natural features:
Tree throws, tree bowls and the difference between them; palaeochannels; periglacial striations and other local geological oddities (manganese and iron pan too).

And maybe some pre-industrial farming stuff too:
Early field drains, hay stacks (like mini round houses, almost) and local specialities.

It would be really nice if units could donate good, clear photographs with the relevant details, such as the type of feature, why it was recognised as such, the geology of the site and any other info they might wish to share.

Since I’ve not introduced myself properly yet, Hi! This is a great site and I wish it’d been around when I started out!!!! It’s to archaeology as to what sex-ed is to schools!

[BAJR Host]

thanks for that... and also apologies for the wierd characters... I am working on this right now!

And yes... that sounds like jsut the thing that BAJR would love to host.

"I don't have an archaeological imagination.."
Borekickers