When the Saxon/Norman church was demolished in 1876, it was found that the old tower had been built on a circle of 12 Sarsen stones. They were described as "A Druidical Temple" at the time and the builders blamed the difficulty of working around them as one of the reasons for the cost/time overrun of the new church. This was designed by the famous Victorian architect Sir Alfred Waterhouse (Nat Hist Mus, Manchester Town Hall etc.) and he put the new tower on the site of the old and used the old circle again for the foundations. A nice example of one religion imposing itself on another.
In the churchyard there is a fine yew-tree, which according to local tradition is approximately five hundred years old, although its exact age is unknown. (See the Waypoint)
'There is an unusual concentration of Sarsen stones in the village, including a ring of twelve which form the foundations on which the towers of both the present church and of its medieval predecessor were built, (I’ve included a Waypoint where you can see some evidence of this at ground level) and two close to the wooden bridge over the river at Berry Lane. You will need to find these.....
According to local folklore, the twelve stones originally stood as an upright circle on a mound near the site of the church. A Charter granted in the year 972 AD, in the reign of King Edgar, refers to an 'Egsanmor' (slaughter stone) at Twyford. It is from bits of evidence such as these that the legend evolved of a Druidic religious site having existed in the village in pre-Roman times - perfectly plausible, given the proximity of Bronze Age (ca 1500 BC) and Iron Age (ca 1 AD) settlements on the hill later named after St Catherine and on Twyford Down.'
Geology
Types of Building Stone
Building stone, also called dimension stone, derives from one of three naturally occurring rock types:
Igneous - Hard and non-porous rock formed from the slow or quick cooling of molten magma. The best example is granite.
Sedimentary - A fairly porous rock formed from deposits of eroded pre-existing rock that settled in layers mostly on sea beds, and became compacted. The best examples are sandstone and limestone.
Metamorphic - Hard and non-porous rock formed from pre-existing rock that has been altered by intense heat or pressure. The best examples are marble and slate.
There are huge variations within each of these rock types, caused by specific mineralogical and geological conditions, and while any stone can be used for building, they each have constraints that make them more or less suitable for different purposes. Granite, sandstone and limestone can all be used for building walls, although slate due to the way it splits makes an ideal roofing material. Some types of granite can contain mineral salts that cause spalling, where the outer face of stone falls off; slate can contain harmful minerals that break down on exposure to the atmosphere causing stone damage; and sandstone can be too porous and fragile for load-bearing structures. An understanding of how the rock material was formed will reveal how it can be used in a building, what its limitations are, and how it will weather over time.
Sarsen stones (an example of sedimentary to metamorphic)
Sarsen stones are sandstone blocks found in quantity in the United Kingdom on Salisbury Plain, the Marlborough Downs, in Kent, and in smaller quantities in Berkshire, Essex, Oxfordshire, Dorset and Hampshire. They are the post-glacial remains of a cap of Cenozoic silcrete that once covered some areas of Southern England – a dense, hard rock created from sand bound by a silica cement, making it a kind of silicified sandstone.
Many Sarsen stones are blocks of quartzite, often found above the Chalk, and most famous for their use at the major stones of Stonehenge (in addition to the Bluestones - dolerite).
Quartzite (from German: Quarzit) is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe2O3). Other colours, such as yellow, green, blue and orange, are due to other mineral impurities.
When sandstone is cemented to quartzite, the individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals. Most or all of the original texture and sedimentary structures of the sandstone are erased by the metamorphism. The grainy, sandpaper-like surface becomes glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization and metamorphosis. This causes streaks and lenses to form within the quartzite.
Flint
Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white or brown in colour, and often has a glassy or waxy appearance. A thin layer on the outside of the nodules is usually different in colour, typically white and rough in texture. From a petrological point of view, "flint" refers specifically to the form of chert which occurs in chalk or marly limestone.
As a building material
Flint, knapped or unknapped, has been used from antiquity (for example at the Late Roman fort of Burgh Castle in Norfolk) up to the present day as a material for building stone walls, using lime mortar, and often combined with other available stone or brick rubble. It was most common in parts of Southern England, where no good building stone was available locally, and brick-making not widespread until the later Middle Ages. It is especially associated with East Anglia, but also used in chalky areas stretching through Hampshire, Sussex, Surrey and Kent to Somerset. Flint was used in the construction of many churches, houses, and other buildings, for example the large stronghold of Framlingham Castle. Many different decorative effects have been achieved by using different types of knapping or arrangement and combinations with stone (flushwork), especially in the 15th and early 16th centuries.
Flint Walling is traditional to East Anglia, the South and the South-East of England. Both field and shore flints are used. The flints used for walling are up to 300mm in length and from 75 to 250mm in width and thickness. The flints or cobbles may be used whole or split to show the heart of the flint, and also knapped or snapped so that they show a roughly square face. Flint walling is built with a dressing of stone or brick at angles and in horizontal lacing courses that level the wall at intervals. Illustration (a) is of whole flints laid without courses in brick dressing to angles and as lacing and (b) is an illustration of knapped flints laid to courses in stone dressing.
In order to log this EarthCache, please either email me or send me a message via the Message Centre, with the answers to the following questions:
- Observe the church building, describe the composition of the pebbles used to make the main sections of the walls?
- What rock type are they?
- Go to the Waypoint for the “visible stones”, these are possibly some smaller worked Sarsens here at the base of the tower. How tall is the tallest one?
- For bonus points what are the co-ordinates at the Sarsen stones found on Berry lane?
- Optional: Upload a picture of you and/or your GPS with the Church in the background in your "Found it" log.
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For full information on how you can expand the Church Micro series by sadexploration please read the Place your own Church Micro page before you contact him at churchmicro.co.uk
See also the Church Micro Statistics and Home pages for further information about the series.
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