NLM-41D6C6: Roman lead cistern base in situ

Rights Holder: North Lincolnshire Museum
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Rights Holder: North Lincolnshire Museum
CC License:

Rights Holder: North Lincolnshire Museum
CC License:

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VESSEL

Unique ID: NLM-41D6C6

Object type certainty: Certain
Workflow status: Awaiting validation Find awaiting validation

A telephone call received on the afternoon of Sunday 13 September 2020 alerted this reporter to the discovery of a large lead object on a Roman site outside Rudston, East Riding of Yorkshire, by two metal-detectorists. I agreed to attend to view the site the next day, with a view to the archaeological retrieval of the object if feasible.

A cast lead flat-based cylindrical vessel with an internal fringe of projecting iron nail shanks, driven from the outer side, was identified. The object was 600mm in diameter, flat-based, with a plain squared rim at the top of a vertical wall 100mm high and of a uniform thickness noted to be 10mm on site. More detailed measurement showed the wall thickness close to the rim to vary between 8.6 and 13.8mm, though 11mm would cover the majority of measurements taken. On-site, surviving nail lengths were estimated as 40mm within the vessel, spaced 45mm apart. A single nail-end projected so as to suggest an original length of 60mm for all of the nails, but was lost in the course of excavation. More detailed recording, after the object was lifted,  identified 42 nail positions, of which the nails were entirely lost from seven sites, with six more represented by shanks broken off short. The more completely surviving nails were between 27mm and 36mm in length [measured from the inner wall of the vessel] with shanks of c.7mm thickness, and with rounded slightly plano-convex heads of diameter c.17mm in most cases, but with a few possibly dome-headed. The spacing of nails was between 48 and 38mm centre-to-centre, with some lesser values probably arising from distortion of the vessel wall. They were set c.14mm below the slightly chamfered plain rim of the lead vessel [again measured on the inner side], with slight variation from nail to nail. They may have been intended to pass into, rather than between, the strakes of a substantial wooden vat or barrel: if two nails passed into each strake, this might imply a wooden structure of 21 strakes. If the survival of nails arose from their protection by wood, this could suggest a wooden vessel with a wall of about one inch thickness, which would be rather more substantial than a simple reused barrel.

The object occupied the base of a circular pit of 750mm diameter cut 400mm into chalk subsoil. The pit had been dug at the end of an ash-filled channel 0.65m wide and alongside the tumbled rubble of a wall footing. The footing included chalk rubble and sandstone quern fragments, and part of this structure had collapsed over the leaden object after its disuse. Roman pottery and burnt animal bone was recovered from above and below it. The object has yet to be weighed, though moving it was a two-person job.

It is inferred that the object was the nailed waterproof end of a cylindrical or barrel-shaped tank, cistern or pump base. The use of lead implies a connection with water supply or storage. It had been installed within or immediately adjacent to a pre-existing structure, and at one end of an ash-filled linear feature.

Suggested date: Roman, 100-410

Notes:

Interpretative notes (of 15 September, the day after fieldwork):

The nails and their good survival tend to suggest the secure attachment with hand-made square-section nails of a lead end to a wooden barrel with walls at its end of thickness 40mm. The complete loss in all but one cases of the nail tips may be due to their corrosion if they had projected beyond the inner surface of the now-vanished wooden vessel, perhaps during its working life. While it survived, a wooden barrel would have prevented the movement of the adjacent wall footing. Its decay would have permitted the subsequent collapse of the wall footing over the SW edge of the vessel. This collapse may have caused localised distortion of part of the vessel wall.

The absence of part of the series of nails – whose punched holes remain clearly discernible on the inner side of the vessel – coincided with the distortion of its wall, a point which has a bearing on the state of the putative assembly of wood, lead and iron when it was inserted. However, these nails may have been entirely lost to corrosion because of moisture admitted by the more freely draining wall footing. Elsewhere, ashy material within, around and below the object may have promoted an airless environment and thus promoted their more robust survival.

A barrel-lined well shaft or cistern is a familiar structural form from medieval waterlogged contexts. If such is to be inferred here, the function should perhaps be as a cistern or the base of a syphon-operated water pump. Water supply is a persistent constraint of activity on the top of the Yorkshire Wolds. The collection and storage of rainwater may well have been necessary for year-round occupation on the Wold top, and these would be facilitated by the availability of lead in sufficient quantity for its deployment in structural uses. This was only achieved from the Roman period onwards. The evidence for the use of lead in water supply may often have been removed for later reuse, the evidence for which is ubiquitous in rural areas of Roman and later activity.

The ashy nature of soils in, around and adjacent to the object might point to some connection with the functioning of an oven, kiln or corn drier. This, however, pre-dated the insertion of the object. Ovens and corn driers would have been necessary in domestic and agricultural regimes respectively. A pottery kiln would usually be expected to exhibit more convincing evidence of in-situ burning of its sides and base, and more abundant pottery and waster fragments than were retrieved by the hand-excavation of c.0.4 cubic metres of soil. Limited patches of possibly burnt friable yellow-brown clay were observed in or over the vessel within the compacted ashy matrix. However, if this material was locally present when the putative cistern was emplaced, it may subsequently have washed into and around the vessel, either during or after its use. This could explain the intimate relationship of ashy silts to the outer wall of the vessel, which they lay against, as well as their appearance within it. The latter may only have occurred after the decay of wooden elements of a barrel cistern.

The availability of a robust purpose-made lead base – and indeed the many iron nails required for its secure attachment to the end of a barrel or cylinder of wood – both point to engagement of this site with a well-resourced centre. The Rudston villa, with mosaics evidencing high-status occupation spanning the 2nd to later 4th centuries, is a well-known local focus lying within the same modern civil parish. The settlement whence this discovery comes was extensive, probably part of a ladder settlement, and has produced many more already-recorded portable antiquities dated from the 1st century to the mid-4th.

Find of note status

This is a find of note and has been designated: Potential for inclusion in Britannia

Class: Cistern base

Subsequent actions

Subsequent action after recording: Undergoing further examination at a museum

Chronology

Broad period: ROMAN
Period from: ROMAN
Period to: ROMAN
Date from: Circa AD 100
Date to: Circa AD 410

Dimensions and weight

Quantity: 1
Height: 100 mm
Thickness: 10 mm
Diameter: 600 mm

Discovery dates

Date(s) of discovery: Monday 14th September 2020

Personal details

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Other reference numbers

Other reference: NLM46537

Materials and construction

Primary material: Lead
Secondary material: Iron
Manufacture method: Cast
Completeness: Complete

Spatial metadata

Region: Yorkshire and the Humber (European Region)
County or Unitary authority: East Riding of Yorkshire (Unitary Authority)
District: East Riding of Yorkshire (Unitary Authority)
To be known as: Rudston

Spatial coordinates


Grid reference source: GPS (from the finder)
Unmasked grid reference accurate to a 1 metre square.

Discovery metadata

Method of discovery: Metal detector
General landuse: Cultivated land

References cited

No references cited so far.

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Timeline of associated dates

Audit data

Recording Institution: NLM
Created: About one year ago
Updated: About one year ago

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