VIKING UNST PROJECT: FIELD SEASON 2008 - Nabo

minerals are chemically stable in natural earth surface conditions, and both are commonconstituents of sedimentary rocks, having survived cycles of large scale denudation,transport and redeposition spanning many tens of millions of years. Three other mineralsare commonly present in the schist, but only in minute quantities. Biotite and chlorite arechemically stable in most natural conditions, although they do not normally survive thephysical rigours of the denudation-to-redeposition cycles. Calcite will dissolve in acidicgroundwater but it seems unlikely that there is sufficient calcite in Eidsborg Schist evenpartly to desegregate (i.e. loosen) the quartz and/or muscovite and so produce the smallscaleerosion observed.3.2.3 Steatite and related schist artefactsTHE ASSEMBLAGE FROM THE UPPER HOUSE, UNDERHOULLBake platesThere are three finds within this category made of schist, SF647 (context [185]), SF1799(context [189]) and SF1212 (context [053]). Of these, only SF1799 is definitely a bakeplate fragment, and it is large, measuring over 150mm across and just 9mm thick with toolmarks around the edge. Each of these finds does however lack the detailed grooving seenon one or both faces of the finds from Hamar 2008. The type has been discussed in relationto the examples from Hamar 2008 (below) and commonly the stones identified as schist areusually considered to be Scandinavian imports, whereas the ones identified as steatite areconsidered to be from Shetland and of a slightly earlier date. In this case certainly thethickness would seem to support an origin within Shetland rather than it being an import.VesselsThere are 102 finds which have been identified as parts of vessels; around 20 of these areclearly worked pieces which are likely to be vessel sherds, but which survive in a formwhich is either too fragmentary or undiagnostic to be certain. Amongst the sherds whichcan be clearly distinguished, there is a variety of vessel forms to be seen. The morecommonly identified hemispherical form is represented for example in SF1529 (context[190]) and there is a variety of wall thicknesses to be seen throughout the assemblage inthis form (eg SF1415, (context [168]) has a thick wall measuring some 23mm whereasSF1092 (context [149]) mm is thin walled (only 8mm). Flat bottomed vessel forms areindicated by SF1063 and SF1064 (context [138]), and in some examples these are clearlyfrom squared vessels (such as SF831, context [074]) and the corner sherds SF1487 (context[169]) and SF1094 (context [123]). Other forms include more unusual examples of troughs,for example, SF1062 (context [074]), and SF867 (context [142]) is clearly oval in form andmay have been trimmed down slightly.There is a great variety in the thickness and indeed finishing treatment of the vessel walls.SF1965 (context [050]) is a large vessel of thick walling some 17mm across, and SF1957(context [185]) is slightly thinner at 12mm. This latter sherd has also very smooth inner andouter wall surfaces in contrast to SF1983 (context [213]) which is from a thick walled largevessel whose surfaces are deeply gouged. Very fine walled vessels are indicated by anumber of sherds, such as SF702 (context [074]) and SF803 (context [070]) and37