Comparison of Rayleigh and Eastwood Churches

December 22 2006. Measure all the London Clay concretions seen in the exterior of St. Lawrence and All Saints Church, Eastwood in Essex for comparison with Prittlewell Priory who held it as a chapel from about 1110 to the establishment of a rector in 1248. Probably this means that the Cluniacs were given what is now the Norman Nave built a few years earlier and that no further work was done with the tithes until the independent rector added the present Tower, Chancel and South Aisle walls, described as early 13th Century in architectural guidebooks. There are some later walls and an entirely red brick 16th Century South Porch which contain no London Clay materials; the bricks probably being made for sands and flint gravels of the second terrace mapped by the Geological Survey around the brook 0.3 to 1.1 km west of the church. These bricks have a similar colour on fresh faces (10R 6/6) to those made from well sorted coarse silts and very find sands of the Eocene Claygate Member in the Rayleigh South Porch, but contain obvious white and black pebbles in old bricks of dimensions 214 mm by 105 mm by 57 to 62 mm. Associated finer-grained bricks with dimensions 226 mm by 105 mm by 47 mm also have Pleistocene-derived flints in them. The Rayleigh South Porch is said to date from just before 1497 and has a granule-grade grog consisting of iron oxide concretions, yellow laminated sand clasts and similar sandy clay flakes; all of which could have come from the Claygate Member of the London Clay exposed around Rayleigh Church and Castle. The average and more uniform brick dimensions in that porch are 218 mm by 116mm by 58.5 mm. Previously measured Rochford Church tower bricks of similar age averaged 233 mm by 116 mm by 58.5 mm, and are derived from Pleistocene silts and sands in the Rochford Buried Channel under both Rochford and Eastwood Churches. At Rochford the coarse particles or grog included by the brickmakers consists of white and grey sandy clasts of dimensions 6 mm by 5 mm presumably made from calcareous concretions or previously dried silts of Pleistocene age. The Rochford tower was built for the grandfather of Anne Boleyn who died in 1515 and unlike the Eastwood and Rayleigh Churches his brickmakers made additional black bricks of similar size to produce diapers on the red brick tower. At Rayleigh this pattern was made in or shortly after 1515 by placing black flints among the Kentish Ragstones and septaria of the Alen Chapel, east chancel wall and some buttresses. It was not attempted in the South Porch probably because it was built before that fashion had developed and it was attempted at Eastwood.

Turning now to the London Clay concretions there is just one seen in the largely hidden walls of the Norman Nave. Since it contains no thick veins on the original exterior and differs in colour from those in the 13th Century walls it may perhaps be regarded as a questionable septarian record. The average colour measured from three parts of it in the freezing fog is 5.0YR 3.67/3.33 and in a previous visit in the bright afternoon weather of October 3 2005 it averaged 6.67 YR 4.00/3.33. Two parts of it were recorded as dark yellowish orange (10YR 6/6) and blackish red (5R 2/2) in both weather conditions by holding the Rock Colour Chart colours in the same light as the wall enveloped by the grey background cardboard of the chart. A third area of the concretion was recorded as Greyish Red (5R 4.2) in the sunshine and as the reddish brown (10R 3.2) today. With more experience I think that this concretion is from the London Clay, probably from Southend, and matches the red variety seen in Leigh Church tower, the Norman walls at South Church and Sutton churches and some of the Prittlewell Priory and Rayleigh Church septaria. By contrast the London Clay concretions in the Chancel and South Aisle at Eastwood are of a different colour and provinance with an average colour of their matrix measured today from 8 fragments and 24 areas of colour as 7.708 YR 6.208/3.33, changing to 7.692 6.269/3.341 with the addition of two vein colours seen on one of them (marginal prisms 5Y 8/1, central prisms of upsplit 4 mm thick vein 10 YR 6/6). Bearing in mind how small and scarce these concretion fragments were one should not assume that they do not come from thicker veined concretions seen at Southend, or were not bored by modern beach organisms. On December 14 and 18 I revisited Rayleigh Church and recorded all the colours on the London Clay concretions in the lower external wall of the most eastern of the four bays in the South Aisle, and also in what appears to be a later wall built around the post-1394 Ragstone tower forming a thicker west wall of the western bay to the South Aisle. The eastern bay include previously fallen concretion fragments showing Eocene high spired microgastropods (perhaps Litopia sp. or Spiratella tutulina (curry) and the west wall shows some calcite replaced wood with bivalve borings of Eocene age in it (3 mm diameter Teredolites longissimus Kelly and Bromley. The claystone matrix of the fallen fragments, of both grey unweathered and red veined lithology is full of coarse silt and very fine sand in a bioturbated clay matrix. The veins all have a pale yellow prismatic margin, followed by dark orange as at Eastwood, and then when thick enough another pale layer of open scalecohedral calcite prisms with a dark surface on the open vein. In one case this dark manganiferous oxide layer was overgrown by a 20 mm diameter rostette of white barite fibers, as at Prittlewell Priory. In terms of the average colours of the matrix and jointing in the western wall of the South Aisle was 2.22 Y 6.833/2.500 (18 determinations), the new insitu measurements of east bay 8.65 YR 6.294/3.024 (85 determinations) and the December 4 Choir Vestry 10.0 YR 6.229/3.057 (35 determinations). They all show the same sequence of veins and I do not doubt that all these walls were built from the same concretions, probably present on the site and perhaps left institu in the east bay wall when the church was repaired and extended in 1394. The sequence of vein cements is most characteristic at Rayleigh and obviously produced a variable average vein colour there recorded as follows: west wall (5) 9.00 YR 6.200/4.800. East Bay (20) 0.30Y 6.100/2.900, choir vestry (4), 2.50Y 7.500/3.000. This was an exposure of highly disturbed brown London Clay with similar thick-veined septaria of grey to brownish red colour on the upper beach about 110 metres east of Crowstone Avenue on December 20th and I intend to compare the samples to these similar-looking Rayleigh and Eastwood Church septaria over the holiday when dried.

Rock colours at Prittlewell Priory

December 13 2006. Visited Prittlewell Cluniac Priory to check similarities between the septarian London Clay concretions formerly exposed in the foundations of the south transept of the Priory Church and those in the south aisle at Rayleigh Church potentially built before a rector was established there in 1314. Before that the Cluniacs of Prittlewell potentially had some involvement in Rayleigh Church. Around 1164 Thomas Beckett gave them some control over the Milton manor, (now Westcliff-on-sea and eastern Southend) which was held by the monks of Canterbury for their own supplies since 959 (Canterbury continuously Southchurch, presumably the coast east of the pier continuously since 823). The supplies doubtless included division D and perhaps E London Clay septaria used to rebuild the priory church in stone at the end of the 12th Century, after it was founded with no control over the coastal manors around 1110. This priory was dissolved in 1536. Since little local church building took place after that reformation until the Victorian era it is unlikely that any of the stones from the partly demolished priory can now be seen off the site. There is, however, an old, but post-1536 vintage wall showing the priory septaria in similar weathering conditions, on the north side of the cloister. Today I measured a north facing patch of these septaria and one or two in the cross-section of the wall using the Geological Society of America Rock Colour chart as at Rayleigh, Hadleigh, Broomfield etc. A patch if relatively wet and lichen-covered foundations near where the Chapter House passage would be in a monastery cloister (i.e. S.E.) was also measured and added to previous data from the now covered South Transept near the new wall (i.e.N.E.). The septarian veins were up to 11 mm thick and composed of prismatic calcite of variable lightness value and much less chroma than either the calcitic matrix of the host concretion margins or of the similarly thick and banded veins at Rayleigh. They do in fact match the scare septaria in the east nave at Hadleigh much better than the Rayleigh septaria and require a separate analysis of vein and matrix colours during averaging. Often there are hardly any vein surface colours to be seen in a church and their inclusion makes little difference to the average dominated by ferruginous sepatarian joint surfaces, weathered exteriors showing Eocene burrows and modern marine borings by Polydora and internal exfoliated calcite claystones. This is the case in the new and rather wet Chapter House passage concretions which averaged 7.576 YR 5.485/3.273 in a set of 33 colour determinations from all the orange concretions there. The undivided data from the new wall averaged 7.754 YR 6.217/3.174; with the lightness value 6.217 increased by factors such as drying and lack of lichen to the condition seen in church walls and dried polished sections. The chroma saturation of 3.174 is slightly less because the new wall contains a more varied sample of the concretions from the priory, and the hue is shifted from red to yellow because of them and the inclusion of the calcite veins in the data set (69 determinations).
It needs to be explained that hues re averaged by imagining that the yellow-red (YR) scale continues through all the hues in a manner that produces small then negative numbers in red haematitic oxidation surfaces (i.e. -5 for hue 5.0 R) and large positive numbers for reduced iron purple-blue colours (i.e. +65 for 5.0 PB). Since most of the concretions are brownish the average is in the YR scale; but it can shift into the yellow scale Y when the matrix is a largely unweathered olive grey colour and pure calcite vein surfaces are exposed. Hues reported as such and such Y should have ten added to them when plotted or compared with averages still in the zero to ten Yellow-Red scale.
Vein surface measurements exclude the barite rostettes in the middle of the septarian cracks, which provide important provinance, clues. In the South Transept sea-worn and Polydora orange (10YR 6/6) concretions had rostette diameters of 20 mm, compared to 22 mm for the one in a similar matrix in the South Aisle Rayleigh. However, the averaged vein colours in all the determinations from the Priory site are much closer to Hadleigh and showed no more barite today.

Hadleigh E Nave veins (2) 2.50 Y 7.50/3.00

Hadleigh E Nave matrix (14) 6.4 3 YR 5.57/3.57

Priory x wall veins (21) 1.905 Y 6.33/2.38

Priory x wall matrix (93) 6.720 YR 5.96/3.56

Rayleigh Choir Vestry veins (4) 1.125Y 5.57/2.75