© Copyright John Palmer. This is work in progress, last updated 2011-03-22. Please use this link to send me comments and suggestions.
Frances Griffith, Devon County Archaeologist, has given me this description of the alleged `legionary standards': ``A portion of a life-size Purbeck statue of an eagle, suspected of having stood with a life-size Jupiter in or near the headquarters building of the legionary fortress at Exeter. Kept at and often on display in the Royal Albert Memorial Museum, Exeter. See JMC Toynbee in Bidwell PT 1979 pp. 130-2.'' See my abstracts.
PM mortars and pestles have been found at Corbridge. At Exeter, besides the Eagle mentioned above, much PM has been found on the site of the legionary base, which was founded by Legio II Augusta; see Bidwell, 1979 and 1980.
An exhibit at the Coach House Museum, Langton Matravers, seen in 1996, contained the statement that 24 beds were recognised by quarrymen. Clearly commercially useful beds were meant, for Clements (1992), in his description of the type section of the Purbeck beds at Durlston Bay, recognises ten times that number of beds.
Clements' bed DB244 is the upper PM, and DB241 the lower PM. House 1993 recognises a third PM bed which is probably identical with Clements' DB237. The colours of the beds are given as
It is said () that the PM becomes bluer as you go west, in exposures such as that at Worbarrow (Ensom PC 1984). All the Marble beds contain a closely packed mass of shells of the freshwater gastropod Viviparus cariniferus (syn. Paludina carinifera).
Clements' bed DB220 is the Broken Shell Limestone; the name describes its nature exactly. Its `characteristic fossil' is not a single species as with the Marble, but a mass of broken shells of different kinds of molluscs, especially bivalves. It is the same as the `Burr stone', bed 2 of the Coach House Museum list, and as Bristow's bed 78 (Delair and Lander 1972). Bristow calls it the `Soft Burr'. Soft, however, it is not, for it forms the resistant ledges off Peveril Point (Arkell 1947 p.137-8). There is no doubt that it is the Purbeck Burr of commerce (and of many mortaria), but the term `soft' indicates perhaps a confusion (in Bristow) between this `Burr' and the tufaceous `burrs' that form around fossil treetrunks in the Lower Purbeck Dirt Beds, which are seen most notably a little way east of Lulworth Cove (Arkell p.140-1).
I think that the `thornback' is to be identified with Clements' DB123.
The upper Purbeck beds are now recognised as coeval with undoubted Cretaceous beds on the Continent, and the division between the Jurassic and the Cretaceous is set within the Purbeck beds, by some at the level of the Cinder Bed (Clements DB111).
This snail is now referred to the living genus Viviparus and so called more properly Viviparus cariniferus.
I think that much of the Purbeck roofing material found in S Wiltshire, NE Dorset and W Hampshire is likely to have been quarried in the local outcrop of the Purbeck beds near Tisbury. (I have now developed this argument in PDNHAS vol.130.) The only other significant outcrop of these beds outside SE Dorset is at Swindon, where signs of Roman quarrying have been found. No Purbeck Marble is available at either of these sites.
G T Denford has recently made available his inventory of over 3000 Kimmeridge shale artefacts, and associated bibliography, through the Archaeology Data Service.
I got this back to front. The majority of the house had Purbeck stone roofing; the stokehole was an exception, being tiled, as shown in the detailed account.
I have now read Pliny's Latin (Nat. Hist. 36 ix), and it does not refer in any way to the use of multiple-bladed saws. It does describe cutting stone by pressure along a narrow line with the use of sand, which (to me) implies a toothless saw, but in no way a multiple one; compare the findings from the Norden excavation. The Fishbourne evidence is doubly interesting in that it suggests early use of a technique (multiple-bladed saws) which is not mentioned by Pliny.