Septaria at Hadleigh church, Essex

November 10 2006. The Church dedicated to St. James-the-less in the middle of the A13 road at Hadleigh was visited today for comparison of the London Clay concretion colours with the northern Essex church visited a week before. They were both largely Norman structures but at Hadleigh the stone was largely transported over the Thames from Kent in the early exciting reign of King Stephan (c.1140); probably as a secular defense measure by the church authorities. The eastern and western ends of the church were respectively repaired with the same and some new stone in 1854 (following collapse of the semicircular apse) and 1949 (following 1934-45 aerial bombing). A greater obscuration of the original fabric is due to the construction of a vestry in 1928 outside the northwest nave and a small wooden south porch in the 18th Century. There is no external tower only a wooden one on interior nave posts.

The first circuit of the exterior showed only one possible London Clay concretion in the lower two metres of all the old walls. The second more careful circuit provided a sample of colour measurements from ten stones and during a restudy of these particular stones on a third circuit this sample was reduced to 16 colours determined from four stones near the eastern ends of the nave and 8 colours determined from four less clearly London Clay concretions in the south wall of the chancel and the S.W. region of the nave beyond the porch. That corner included a probable glacial erractic of silica cemented, non-Cretaceous sandstone, with dimensions of 450 mm by 450mm that were larger than the Cretaceous sandstones and siltstones blocks obtained from Kent. There were also a few somewhat smaller slabs of ferricrete (iron oxide cemented flint gravel) in the south and west nave.

The largest stone of clearly London Clay origin had exposed dimensions of 220 mm by 180 mm shaped by splitting a concretion along prismatic calcite veins of 5 mm maximum half-thickness flanked on both sides by dark grey to moderate red, originally pyritic joint surfaces (5R 4/1-5R 4/4). The matrix of finer-grained calcite cemented clay graded from this colour, through paler browns and oranges, to a worn rather than a bored exterior weathered yellowish grey (5Y 7/2). Adding what appear to be beach-worn pebbles of the claystone matrix, the average colour of 16 studied spots is 6.56 YR 5.813/3.500 of the Munsell Co. system (i.e. roughly yellowish orange). The provinance is not the same as Broomfield Church as the veins were thicker and more pyritic but it is still unclear whether it represents division A3 of the Reculver-Herne Bay coast in Kent, or the division D/E boundary septaria which can still be found in Hadleigh Cliffs below and east of the subsequently built castle. The sea-worn appearance of some of the stones is of course opposed to that idea since Hadleigh Castle has old marshland separating it from the sea. But if the Kentish stones were landed at the more convenient port of Leigh and had their oyster-shell mortar added there i.e. even now a few whole oyster shells can be seen in the apse) then this objection is overcome. The more doubtful additional 8 colour determinations from four rather less weathered, silty-looking angular stones averaged 1.25 Y 5.750/2.875, which is roughly yellowish to olive grey. If it is reasonable to add them the general average from Hadleigh Church only shifts to 8.12 YR 5.792/3.292, which is yellowish orange. I suspect that the whole modern oyster shells used to make the mortar between the Kentish ragstone and other imported superior building stones came from London Clay shorelines on both sides of the Thames estuary. Some septaria were therefore collected with the future mortars up until the end of Church building with the reformation. It is therefore worth looking for London Clay concretions and recording their weathered colours etc in South Essex walls which are not supposed to contain them in published descriptions. Conversely when the London Clay concretions are common enough to have been noticed by visitors with more general interests, then they probably came from specific sites along the Essex or Kent coastline where they were gathered as building stones in an earlier period ending around 1200. There alternative perspective might be that a few concretions were like the Roman brick and tile fragments also seen in small numbers at Hadleigh Church and most south Essex churches, and came from the use of Saxon or Roman buildings as quarries in stone-poor Essex lands. A third idea, which I think is less likely, is that the insitu septaria seen now in fields such as those near Hadleigh Castle, were formerly gathered as additional building stones from each manor. Much will depend on how stable London Clay slopes were in ancient times when ploughing and excavation work was less easy than in modern times. However, it is relatively easy to test this local hypothesis by comparing the colours and weathered textures of church concretions with those found locally today.