Building Materials: The Stone - House 1

Dr Kevin Hayward

Aims | Introduction and methodology | Petrological identification and geological source (Periods 3 and 4) | Stone type and function | Chronological summary

Catalogue of Tesserae and their Geological Source: PDF (16 KB)
Catalogue of Stone Finds From The Phase 3 'Link Room': PDF (10 KB)
Stone Data Tables: PDF (27 KB)


The main objective of this report is to determine the function, geological character and (where possible) the geological source of the stone assemblage from the 1998-2004 excavations of the 'House 1' sequence.

Given that the occupation of the sequence of buildings on the 'House 1' site extends over some 200 years, a second objective will be to determine whether or not stone source and function changes over time, perhaps reflecting change in the buildings' status and purpose.

The tesserae, although catalogued separately (Tesserae Data Table), have been included in the chronological summary of this report in order to assess their contribution to the stone assemblage through the sequence. A detailed petrological and geochemical report on the worked stone from the Period 2 Room 6 of Early Roman Timber Building 2 can be referred to in an accompanying report (The Stone - Link Room). A catalogue of stone identifications also accompanies this document (Stone Data Table 1).

Introduction and methodology [top of page]

Worked, burnt and unworked stone collected from all periods of the 'House 1' sequence (including Period 2, Timber Building 2, Room 6 (Object O50034)) amounted to 105 pieces from 42 contexts (Total weight 118.2kg). When considering just the stone retained from the later Periods 2 and 3, quantities are relatively small, with just 24.1kg collected from 37 contexts (Stone Data Tables - PDF 22Kb). These totals, however, do not take into account a very large quantity of nodular flint (upwards of 1000kg) used as foundations for the walls of the Periods 3 and 4 houses and not retained.

All collected stone was examined in hand specimen using a hand lens (Gowland x10) in order to identify the type of rock in use. Comparison was made with the author's reference collection of geological samples.

Petrological identification and geological source (Periods 3 and 4) [top of page]


A very large quantity (upwards of 1000kg) of large nodular flint was identified from the walling of Periods 3 and 4 houses. Only one very round example, probably used for decorative purposes, was retained (C3313).

Number of contexts 1; number of examples 1. Total weight 18g.

Lithological description:

Hard, dark grey/black siliceous sediment that fractures easily.

Geological age:

Upper Chalk Upper Cretaceous

Suggested provenance:

Local material. Outcrops in bands of the Upper Chalk close by, including at Mapledurwell in Hampshire (12km to the south) (Sellwood 1984; 1989).

Lodsworth Greensand

Number of contexts 6; number of examples 12. Total weight 12.7kg.

Nearly all of the Lodsworth Greensand is present as reused rotary quernstone fragments from Masonry House 2 (Period 3) (Object O50019), such as at (C1161) and (C1163). A very common rock type in quernstone production from the late Iron Age to throughout the Roman period and used all over central-southern England (Peacock 1987). Previously identified from the town wall and Forum-Basilica at Silchester (Fulford 1984; Fulford and Timby 2000).

Lithological description:

Olive green (glauconitic) hardened fine-grained sandstone surface with small black wisps of chert which infill the burrows in the sediment. These harder grains facilitate the grinding of foodstuffs.

Suggested provenance

The outcrop of Lodsworth (or Pulborough) Greensand has a relatively restricted geographical distribution sited around the Lodsworth-Pulborough area of West Sussex about 60km south-east of Silchester (Peacock 1987).

Fragment of Lodsworth Greensand quernstone
Fragment of Lodsworth Greensand quernstone

German lavastone (Mayen Lava)

Number of contexts 3; number of examples 6. Total weight 571g.

Small quantities of broken and weathered rotary quernstone fragments, the largest example being from the Period 3 Masonry House 2 (Object O50019) (C2023).

Lithological description

Grey to light-grey hard vesicular lava, containing phenocrysts of white mineral leucite and black minerals too. This is an alkali basaltic rock.

Suggested provenance

The main outcrop is from the Niedermendig (Andernach) region of the Middle Rhine. Distance, via the Rhine and the North Sea, is about 800km to Silchester.


Number of contexts 12; number of examples 30. Total weight 1.7kg.

Present in quantity as gravel make-up and in some walling of Periods 3-4, Masonry Houses 1-3 in Buildings 1 and 2. Burnt 'porcellanous' examples at (C1126) and (C3709) (from the ash layer of a hearth) of fossils including the Cretaceous echinoid Micraster

Lithological description:

Soft, fine-grained, white, homogeneous limestone. Fossils identified include irregular echinoid Micraster.

Geological age:

Upper Chalk Upper Cretaceous

Suggested provenance:

Local material. Thick outcrops close by, with bedded flint, including at Mapledurwell in Hampshire (12km to the south) (Sellwood 1984; 1989).

Chalk rock 'clunch'

Number of contexts 2; number of examples 2. Total weight 114g.

Occasionally present in gravel make-up in the Period 4 Masonry House 3 (Object O50044) at (C1800) (C3396).

Lithological description:

Hardened white compact variety of chalk.

Geological age:

Upper Chalk Upper Cretaceous

Suggested provenance:

Hard condensed layers of chalk are common from the Upper Cretaceous succession of southern England. The Chalk Rock at the base of the Upper Chalk in the Berkshire Downs (Sumbler 1996) is the closest to Silchester and the probable source of this material.

Oolitic limestone

Number of contexts 2; number of examples 2. Total weight 59g.

In addition to the large quantity of architectural fragments from Room 6 of the Period 2 Timber Building (Object O50034), tiny amounts of oolitic limestone rubble have been identified reused in Periods 3 and 4, such as at (C2233).

Lithological description:

Yellow/brown (10YR 7/6) weathered limestone surface, with calcite vein 'watermarks' (Jope 1964) cutting across the sedimentary fabric. This fabric consisted of alternating layers of bioclastic and rounded (oolitic) grains. Identical in character to the architectural fragments from Room 6 (Timber Building 2) in Banded Shelly Oolitic Grainstone (Dunham 1962).

Suggested provenance

Combe Down Oolite/Box Groundstone (Bathonian–Middle Jurassic South Cotswolds). These freestones outcrop along the Middle Jurassic ridge in the Bath–Box region of Avon, approximately 90km to the west of Silchester.

Stonesfield slate

Number of contexts 2; number of examples 10. Total weight 210g.

Small fragments of worked tilestone present only in the Period 4 House 3 at (C1140) and (C1832). Functioned probably as roofing materials.

Lithological description

Hard calcareous mudstone, that splits easily and packed full of small bivalves. Trigonia impressa.

Suggested provenance

The main outcrop at Stonesfield, near Woodstock, Oxfordshire, comes from the Great Oolite (Bathonian), about 50km west of Silchester and accessible by boat. There is evidence for Roman quarrying of this stone at Brimpsfield Gloucestershire (Rawes and Gander 1978).


Number of contexts 1; number of examples 1. Total weight 405g.

One example functioning as a hearthstone (C4170) from Period 3 Masonry House 1 (Object O50037)

Lithological description

Hard fine quartz-rich white sandstone.

Suggested provenance

Sarsen is a local Tertiary sandstone from the surrounding Plateau Gravels of the Silchester-Padworth Common area.

Pebbly/ochrous ironstone/ironstone greensand/friable sandstones

Number of contexts 11; number of examples 12. Total weight 1262g.

All found in the Period 4 Masonry Building 3 among the gravel and clay spreads (C2190).

Lithological description

Rusty-brown friable ochrous ironstone nodules. Some contain small pebbles of quartz and are conglomeratic. Others iron-rich glauconitic sandstones or very friable sandstones.

Suggested provenance

Local materials from the Tertiary Sequences and the Plateau Gravels of the surrounding Silchester-Padworth common area.


Example of Greensand whetstone
Example of Greensand whetstone

Number of contexts 3; number of examples 3. Total weight 7404g.

One large example of rubble (C4592) used in walling of the Period 3 Masonry Building 1. Fine example used as whetstone in Timber Building 4 (C3812).

Lithological description

Hard, green, sometimes shelly sandstones of poor quality.

Suggested provenance

Upper Greensand, unclear where the closest outcrops are near Kingsclere (Sellwood 1984).


Number of contexts 1; number of examples 1. Total weight 465g.

One example (C1397) used in the walling probably associated with Period 4 Masonry Building 3.

Lithological description

Very light grey fine calcareous deposit.

Suggested provenance

Holocene, extensive Tufa (spring) deposits present along the Kennett valley near Woolhampton.


Number of contexts 1; number of examples 1. Total weight 13g.

One flattened worked blade 50mm long.

Lithological description

Red-brown hard fine siliceous rock - quite unlike the local dark grey black local flint.

Geological age

Mesozoic or Tertiary

Suggested provenance

Unclear. Chert is present locally in the Barton Beds at Bagshot (Sumbler 1996)

Stone type and function [top of page]

The principal function of stone from Periods 3 and 4 is as walling material. Otherwise, very little else of what can be described as 'worked stone' was present while these structures were in use.


Flint walls from C4592
Flint walls from C4592

Flint nodules up to 300mm across are extremely common in the walls of the Period 3 Masonry Building 1 (0bject O50018), (C4592) and (C4601). This hard, unyielding siliceous sedimentary rock is an ideal material to use as an external walling material. Given the quantity (many hundreds of examples) used, this must have been a very large logistical operation indeed. The early use of flint in large quantity for walling elsewhere at Silchester would imply that a large local quarry had been opened up for this purpose.

Otherwise, the walling from the Periods 3 and 4 Masonry Buildings 1-3 uses relatively small quantities of reused greensand quern fragments and ceramic building material. The rotary quernstone fragments are nearly all found in the internal walling of the Period 3 Masonry Building 2 (Object O50019). The absence of greensand from the external walls probably reflects the vulnerability of the green mineral glauconite to physical and chemical weathering. Isolated examples of local Tufa and Upper Greensand have also been identified, and occasional lumps of chalk.


Only some very small quern fragments (571g) of a weathered German lavastone from the floor levels, e.g. (C2023) of Period 3 Masonry Building 2, appear not to have been reused as construction materials. This hard vesicular volcanic rock was an ideal material for grinding foodstuffs and was found in quantity on many other rural and urban Roman sites of south-central England.

The remaining quernstone fragments (12kg in total) from the 'House 1' sequence all appear to have been reused as walling material as at (C1161) and (C1163). These are all greensands of the Lodsworth variety. The presence of the harder, darker chert here would have facilitated the grinding of foodstuffs. They all appear to be large (up to 340mm across), rotary quernstones with a good example of a lower 'nether stone' present at (C1161, FSF03229).

Lodsworth Greensand quernstones have been identified from Iron Age and early Roman sites throughout south-central England (Peacock 1987) and Insula IX is yet another context for the use of this stone.

Lower section of rotary quernstone Profile of lower section of rotary quernstone
Lower section of rotary quernstone, Profile of lower section of rotary quernstone

Roofing materials

Very little stone roofing material is present in the 'House 1' sequence. A small quantity (200g) of Stonesfield Slate, a fossiliferous calcareous limestone from Oxfordshire, was identified from the Period 4 Masonry Building 3 (C1140). A much larger quantity of ceramic roofing material from (C1140) merely confirms that the use of stone for roofing was negligible before the late Roman period.


Examples of unworked chalk, flint, sarsen stone and reused Lodsworth Greensand from the 'House 1' sequence have been found burnt. Given that some of these examples are associated with ash layers (C3709) and clay floors near hearths (C4170) it is likely that they functioned as hearthstones. Of interest are two burnt examples of the fossil Micraster (an echinoid) from the chalk (C3709) and possibly (C1126). Whether there is any ritual significance attached to these fossils is unclear.


There are two rubstones. One from the Period 3 Timber Building 4 (C3812), the other from the Period 4 Masonry Building 3 (C1757). These are a hard fine-grained greensand and a fine ironstone, both suitable materials with which to sharpen tools.


Finally, 411 tesserae (800g) of variable size (Allen and Fulford 2004, 14) and geological character are present in Periods 2-4 contexts (Tesserae Data Table). The dominant material (80%) is the yellow-grey dolomite cementstone from the Jurassic of Kimmeridge Bay. Other materials from this locality, including the red-burnt (11%) and orange-burnt (0.7%) mudstones show how important these relatively soft clays and mudstones were in tesserae production. Unprocessed raw materials from (C2025) also show that these mudstones were being shaped at Silchester.

Chronological summary [top of page]

Each period of the 'House 1' sequence is marked by the reuse of different materials for the same purpose (walling). Local flint and chalk, on the other hand, are ever present.

Period 2 c. AD 70/80-c. AD 125/150

Reworked architectural fragments and rubble carved out of Combe Down Oolite from the Bath-Box area (The Stone from Timber Building 2, Room 6) characterise the walling material and post pads from the earliest construction phase. The quantity (90kg) of reworked material, including six architectural fragments, does at least tell us that they were originally used to embellish a very early, substantial masonry structure. It is not clear what the function of this structure was, but it is probable that it derived from elsewhere in the town, perhaps from a bath-house or a temple. The dating evidence also suggests that this structure was dismantled, partly dismantled or went into disrepair early on in Silchester's development, i.e. by the Flavian period.

Early Roman Timber Building 2, Room 6
Early Roman Timber Building 2, Room 6

Occasional tesserae, as cubes of Dolomitic Cementstone from the Kimmeridge Bay area of Dorset (Allen and Fulford 2004), have been found in a few contexts as early as Period 2 (e.g. Object O50043). These may, however, be intrusive as they underlie the masonry buildings of Period 3.

Period 3 c. AD 125/50-c. 200

The first stone phase is marked by a complete absence of the reworked architectural fragments and rubble from the Bath region. It is not clear why this happened but two possibilities need to be considered. First, either the plundered 'supply' of freestone from the early masonry structure had all been used up or, more probably, that the supply of stonework was now being redirected to meet the demands of a newer masonry construction such as the Hadrianic Forum-Basilica, where stone of the Combe Down variety has been identified.

Whatever the reason, the demand for walling stone in the Period 3 houses included the reuse of other materials. Unique to this period is the reuse of quernstone fragments of Lodsworth Greensand in the internal walling of Masonry Building 2 (Object O50019). These are likely to have derived from Late Iron Age or Earliest Roman levels from Insula IX, as examples of quernstones made from this material have been found during excavation. An isolated example of Upper Greensand was also being used for walling.

The opportunistic reuse of architectural fragments of limestone from Bath (90km) and rotary quern greensands from Sussex (60km) in Insula IX also reflects the dearth of suitable local building materials around Silchester. This pattern of reuse also seems to suggest that the supply of stone in Period 3 was ad hoc and a separate, much smaller-scale concern compared with the larger-scale, centralised quarrying operations that were used to construct the public buildings at Silchester, including the amphitheatre (Fulford 1989) and masonry Forum-Basilica (Wooders 2000).

The identification of some lavastone querns and greensand whetstones would indicate that during this phase some food processing and tool sharpening was being undertaken.

The tesserae from this period have all been sourced to the Kimmeridge Bay area of Dorset (c. 120km) (Allen and Fulford 2004) (Tesserae Data Table). Dolomite Cementstone and the red-burnt mudstone identified from the flooring contexts (e.g. C4152) of Object O50037 provides the earliest indication so far that these soft, fine sedimentary rocks were being brought in from afar and used in the mosaic flooring of the Period 3 houses.

Period 4 c. AD 200-250

Period 4 (Object O50044) is characterised by an absence of reused Lodsworth and Bathstone fragments in the walling and a preference for more local materials such as Tufa (walling), greensands (Ironstone and Sarsen (hearthstones and gravel spreads). The large number of tesserae identified from this phase are probably residual, perhaps deriving from the earlier flooring of Period 3. (Fulford, pers. comm.).

The introduction of Stonesfield slate from Oxfordshire for roofing appears to be the only new material to have come into the site from a distance.

All in all, very little worked stone has been identified from this period, marking a downturn in the use of stone in the first half of the 3rd century.


© Internet Archaeology URL:
Last updated: Wed Sept 12 2007