Field Notes 2012Posted by Vince Simmonds Mon, March 19, 2012 19:53:48
Location ST 434 585: Trip to explore the Wimblestone. The stone comprises grey-pink conglomerate/breccia of Triassic age, the surface is pock-marked with a hole through the stone close to the base, clasts are angular to subangular fine to coarse of limestone, sandstone and quartz, it has a substantial covering of lichen in places. The stone has an east/west alignment with the valley, from the slopes of the valley to the west are views of the Severn Estuary and to the southeast the central Mendip Plateau.
Field Notes 2012Posted by Vince Simmonds Mon, March 19, 2012 19:32:30
Location ST 517 487: On a very foggy day took a trip to the Deer Leap stones close to Ebbor Gorge and an interesting exposure of Quartzitic Sandstone Group.
It has been suggested that the stone might date to the Bronze Age. There are some interesting surface features to be noted.
Reference: Adkins, L. and R. 1992. A Field Guide to Somerset Archaeology. The Dovecote Press Ltd.
Field Notes 2012Posted by Vince Simmonds Mon, March 05, 2012 21:27:40
Another long weekend over at Quoit Farm.
Top row of images: some of the surface features of Hautville's Quoit.
Botttom row of images: the small bivalve fossils.
Field Notes 2012Posted by Vince Simmonds Mon, February 27, 2012 08:20:43
Been over at Stanton Drew with the Bath and Camerton Archaeological Society surveying the area around Hautville's Quoit [and the stone itself, of course].
Hautville's Quoit is located at NGR ST 60173/63811 using hand-held Garmin etrex GPS accuracy +/- 5 metres.
Much of the work so far has been concentrated on resitivity and magnotometer as well as EDM survey of the fields. Also some recording of the stone and its features.
Hautville's Quoit is a pale brown to grey sandstone. The sandstone can be described as comprising subrounded to rounded (high sphericity), fine to medium (250 microns), well to medium sorted, shiny polished mostly translucent grains of quartz, that appear matrix supported in a siliceous cement. There are noted numerous small clam-like (bivalves) fossil shells measuring in area up to 10mm x 6mm on some exposed surfaces, these are not yet identified. A white scaly appearance on some parts of the stone are likely to be due to lichen growth or as a result of weathering. The pock-marked surface might be the consequence of a number of factors that are still the subject of ongoing research. The quoit was examined using an illuminated field microscope with x30 magnification and hand lens with x8/x15 magnification, natural light conditions were good at times, the stone has been cleared of debris.
On a purely personal note the rock type that comprises Hautville's Quoit is not one that is recognised either in the local, nor broader surrounding area. There are a number of features of the stone that require some further consideration.
Lloyd-Morgan (1887) described the rock type that comprises the quoit as fine-grained sandstone. Lloyd-Morgan hesitates to offer any opinion as to the source of sandstones found at Stanton Drew, either that of the quoit or the stones found in the stone circle close by and states 'of the source, geological and local I am doubtful', he does, however go on to ask the question 'Is it possible that one or more of the sandstone monoliths may be sarsen - but whence?'.
Reference: Lloyd-Morgan, C. 1887. The Stones of Stanton Drew: their source and origin. Proceedings of the Somerset Archaeological and Natural History Society. 33: pp 37 - 50.
Field Notes 2012Posted by Vince Simmonds Fri, February 24, 2012 08:17:50
While taking a visual survey of the landscape that surrounds the site at Stanton Drew it is of note that at other monument sites such as Stonehenge and Priddy Circles there are a considerable number of other features in the landscape, for exmple round barrows. Why are [or where are] these apparently not seen in the surrounding landscape of Stanton Drew?
This stone, pictured below, is the first reached on the present day access to the stone cicle from Stone Close car park. When this particular stone is compared to others of it's rock type in the circles there is an 'un-natural' look to it, the majority of the other stones are 'block-shaped'. Noticeable on the surface are blackened areas, it is possible these are the result of 'firing' a method used in the past to break up stones. The lower part of the stone still retains, what looks to be a more angular shape. In the 17th century John Aubrey when visiting the site noted that 'as hard as these stones are they a make a shift to break them with sledges because they incumber their good land' (Burl, 1999. p50). Reference:
Burl, A. 1999. Great Stone Circles: fables, fiction, facts
. Yale University Press, New Haven and London.
Field Notes 2012Posted by Vince Simmonds Sun, February 12, 2012 15:14:29
The Cove at Stanton Drew, possibly the site of a long barrow and in close proximity to the stone circle sites.The stones that form the Cove comprise Dolomitic Conglomerate of Triassic age. Some of the clast material and fossils within the conglomerate have been silicified making them less prone to erosion and consequently they stand out from the surface.
The stones have a pock marked surface, this feature is particularly evident on the exposed joint faces when compared to the bedding surfaces. There is also a substantial covering of lichen on the stones.Just a short distance from the stones site in Stanton Drew at NGR ST 5960 6172 are a number of exposures of Pennant Sandstones of Carboniferous age.Close by is the prominent Knowle Hill at NGR ST 5841 6131 the summit has good panoramic views of the surrounding countryside.
The above images show the views to the southwest (left image
) from Knowle Hill summit over Denny Island to Harptree and the Mendips beyond; while to the northeast (right image
) is Stanton Drew, the church is centre picture. It might be possible to see both The Cove and Southwest Circle from this viewpoint, unfortunately there is still some vegetation obscuring the sightlines, but most certainly the Great Circle and Northeast Circle are hidden from view.
Field Notes 2012Posted by Vince Simmonds Mon, February 06, 2012 17:27:45
Took a trip over to Stanton Drew to take a look at the stone circles. It's good to visit at differing times of the year and in different light conditions to give a range of perspectives. During the winter months the vegetation has died back and vistas are so much clearer. I wanted to get some close up photographs and look closer at the texture of the various rock types. The two images above are of the stone at position ST 60045/63309 in the Great Circle. This particular stone comprises sandstone with distinct cross-bedding visible and has layers of fine to medium subangular to rounded gravel of quartz.
The two images above are of the stone at position ST 60034/63322 in the Great Circle. This particular stone comprises oolitic limestone, possibly Inferior Oolite Group of Middle Jurassic age. It has a 'gritty' texture as exposed in the solutional features.
The eight images above are of stones in the Southwest Circle. It is interesting to note the effect of silicification on the clasts and matrix of dolomitic conglomerate and the variation of colour from pale pink to oranges and yellows. These rocks also have a high quartz content and a glassy lustreous appearance.
Field Notes 2012Posted by Vince Simmonds Sun, January 22, 2012 16:49:57
It has been sugggested that Bathampton Down is a possible source for the Jurassic limestone type stones that are seen at Stanton Drew [Great Circle]. As a follow up to this suggestion a field trip and reference to relevant maps (OS and BGS) of the area leads to an initial impression that Bathampton Down is a largely manufactured landscape that includes prehistoric, historic and present day land usage, this currently includes a golf course and university grounds. The scarp that flanks much of the hill summit has been subjected to considerable quarrying and mining activity that has left its mark. The Jurassic limestones seen at Bathampton Down exhibit the typical erosional features that are evident in limestones of this age and type anywhere in the British Isles. There is no natural connection between Bathampton Down and Stanton Drew, transportation of material by river would involve double movement going downstream [to Keynsham] then following the River Chew upstream. A route across land is unlikely; it is undulating and there are no obvious waymark features that suggest a route such as this might chosen. However, it is apparent that the present modern landscape, in all likelihood, has masked patterns and features that might have been obvious in prehistory (Pryor, 2003. p53).
Location ST 77799/65016. A small stone quarry close to the golf course north end of Bushey Norwood (image above) has good exposures of Upper Rags and Bath Oolite (see below for description). Pale creamy-brown oolitic limestone of Jurassic age, the exposed rock has a bleached appearance with pale grey-green lichen. The sequence in the image above from the top has >1 metre of weathered limestone with abundant organic growth overlying 150mm of solid limestone that in turn overlies very fractured limestone. Below to unkown depth is more solid limestone with occassional fractures and apparent bedding layers.
Location ST 77349/65490. There are numerous boulders of limestone in an area containing field systems, pillow mounds and warrens and a number of other features, on the north facing slope of Bathampton Down. The material is described as pale cream-brown very shelly limestone with pock-marked surface of Jurassic age, the rock has substantial lichen growth (image above and two below).
Location ST 77948/64649. Bushey Norwood, the underlying geology in this area comprises Combe Down Oolite. More boulders of limestone and there is evidence of many sub-surface boulders (images above and below).
Geology: Reference to British Geological Survey (BGS) 1:63 000 scale map Sheet 265, Bath shows that the geology underlying Bathampton Down is Great Oolite Limestone, to the eastern side is an area defined as landslip while to the northern and western sides is an area of foundered strata. The BGS 1:10 000 Sheet ST76SE further describes the Great Oolite Group as comprising (in sequence, from the top down):
Cornbrash - rubbly shelly fine-grained limestone.
Forest Marble - grey mudstone, commonly with sandy lenses and partings; sandstone near the top; flaggy shelly and oolitic limestone locally at the base.
Upper Rags and Bath Oolite - streaky cross-bedded shell-fragmental oolite locally with coralline limestone at base and top; overlying oolitic limestone and oolite freestone.
Twinhoe Beds - fine-grained detrital limestone overlying pisolitic limestones; ironshot at base.
Combe Down Oolite - massive shell-fragmental oolite and oolite freestone
Together the Upper Rags/Bath Oolite, Twinhoe Beds and Combe Down Oolite are further classified as the Great Oolite.
Pryor, F. 2003. Britain BC. Harper Collins Publishers/Harper Perennial (2004)
NotesPosted by Vince Simmonds Sat, January 21, 2012 16:54:39
I have often wondered whether lichens might be studied to give some indication of a stones origins. Lichenometry is a geomorphic method of geochronologic aging that uses lichen growth to determine the age of exposed rock: lichens are presumed to increase in size radially at specific rates as they grow. Measuring the diameter of the largest lichen of a species on a rock surface can therefore be used to determine the amount of time that the rock has been exposed. Lichen can be preserved on old rock faces for up to 10,000 years, providing the maximum age limit of the technique, though is most accurate (within 10% error) when applied to surfaces that have been exposed for less than 1000 years. The use of lichenometry is of increased value for dating deposited surfaces over the past 500 years as radiocarbon dating techniques are less efficient over this period (Wikipedia 21.01.2012).
These images were taken in February 2011 at the boulder fields, Garrow.
Field Notes 2012Posted by Vince Simmonds Sun, January 08, 2012 15:24:11
Not so much walking more of a drive around field trip to check up on some previously noted sites, to plot NGRs, and to confirm some of the underlying geology by referencing the appropriate BGS Maps 1:50 000 Scale, Sheets 264 and 280. NGRs have been plotted using a hand-held Garmin etrex GPS - accuracy +/- 6 metres.
Stowey Church ST 59914/59430
There are numerous examples of Sandstone with bedform features, including quartz gravel layers, used in the church construction this is particularly evident in the tower (above and below). The colour is variable ranging from reddish-brown to a pale grey and pink-brown, sand grain size is mostly fine to medium, gravel is sub-rounded to rounded, fine to medium of quartz. I would expect that this construction material was locally sourced. Surprisingly Pevsner describes the church as "small and of little architectural interest" and doesn't give any dates for the phases of construction (Pevsner, N. 1958. The Buildings of England, North Somerset and Bristol. Yale University Press, New Haven and London).
Felton Common ST 51851/64783 elevation 187 metres
Numerous boulders of Ashy Limestone and Tuff of Carboniferous age are seen in the common land and field boundaries (above and below).
At location ST 51625/64910 in a Bronze Age barrow there are several boulders of the same Ashy Limestone and Tuff exposed (below).
Kingdown ST 52831/63626
In a field boundary are numerous boulders of silicified rocks from the Harptree Beds of Rhaetic-Lower Lias Age (above and below). Some of these rocks are quite garish having a bright orange-yellow and orange-red colour (below), they appear to be a mostly fine grained material.
The sequence at Kingdown is Harptree Beds, Lower Lias and Mercia Mudstones, Triassic overlying Clifton Down Limestone, Carboniferous, further to the south are Dolomitic Conglomerate, Triassic strata (BGS Map 1:50 000, Sheet 264, Bristol).
Fairy Toot Long Barrow ST 52057/61825 (NMR 198102)
The rock at this location comprises White and Blue Lias, Lower Lias overlying Penarth Group usually described as the littoral facies at the base of the Jurassic and the Upper Triassic. The Mendip Littoral* area rocks generally comprise cream-grey, coarse-grained bioclastic limestones, pebbly limestones and conglomerates, the clasts are mainly derived from Carboniferous limestone. (*Littoral - beach environment)
Fairy Toot is described as a chambered long barrow of the Severn-Cotswold type consisting of a long trapezoid earth mound covering a burial chamber. Sadly, the site is now mostly destroyed.
Field Notes 2011Posted by Vince Simmonds Sat, January 07, 2012 16:20:00
Maes Knoll, Dundry Hill. Overcast and windy. NGRs have been plotted using a hand-held Garmin etrex GPS - accuracy +/- 6 metres.
At Maes Knoll at the eastern end of Dundry Hill is a small scarp with several exposures of pale yellow-grey Oolitic Limestone of Jurassic age, the rocks have a number of natural solutional features. The scarp alignment is parallel to the contour of the hill.
At location ST 59886/66151 are more exposures of Oolitic Limestone. Much of the rock is obscured by an overgrowth of grass turf and lichens.
At location ST 60193/66139 at the east side of the Maes Knoll site Oolitic Limestone is clearly visible at the top of the ditch close to the surface. Although some of this rock might have been exposed when the ditch [or Wansdyke] was excavated.
From the hilltop in this general location there are good views of the Stanton Drew stone circles and this view is maintained when descending the footpath leading in a southeast direction off the summit of Dundry Hill down towards Norton Malreward. At around 120 metres elevation the view to the stones becomes obscured by buildings and trees.
Field Notes 2011Posted by Vince Simmonds Sat, January 07, 2012 15:10:33
Another overcast, wet and windy day. Today's walk concentrated on an area closer to the stone circles. NGRs were plotted using a hand-held Garmin etrex GPS - accuracy +/- 6 metres.
Stanton Wick to Upper Stanton Drew ST 61078/63188
In the stream-bed of a deeply cut stream valley is an exposure of sandstone bedrock.
Although the rock appears red on surface exposures including fractures and joints when freshly broken faces are examined the rock is grey-black and medium to coarse grained. There is a substantial amount of colluvial material overlying the bedrock, the depth of the valley cut is 5 to 10 metres [or more]. Walking out of the stream valley up to the ridge at location ST 61302/62949 the Stanton Drew stone circles are clearly visible.
[Sandstone exposure is possibly part of the Supra-Pennant Measures (d6b) of the Upper Coal Measures of Carboniferous age. The former Bromley coal mine site is approximately 1km south of this location]
Stanton Wick ST 61378/61120 136 metres elevation
At the top of the hillslope is an exposure of pale yellow-grey silt/mudstone mostly as cobbles and boulders, no bedrock exposure was noted. These rocks are White and Blue Lias of Jurassic age [Reference: BGS Map 1:50 000 Scale, Sheet No. 280 Wells].
Location ST 61378/61113 at 120 metres elevation [just left of centre in the image above] is a curious man-made feature cut into the hillslope and facing north, possibly a stone pit or quarry. On the hilltop above this feature are what appears to be the remains of building(s) and earthworks. Across the hilltop is considerable evidence for human activity probably stone quarrying, ST 60955/60990 is a good example. The small streams that flow down the lane from this area have tufaceous [travertine] properties leaving a coating on pebbles, etc.