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Great Chessells Gravel Pit near Bourton-on-the-Water, Glos, and the occurrence of mammalian remains
Great Chessells Gravel Pit near Bourton-on-the-Water, Glos, and the Occurrence of Mammalian Remains by L. RICHARDSON and K. S. SANDFORD Rece ived 30 September 1958
CONTENTS page 40
1. INTRODUCTION 2. DESCRIPTION OF SECTION 3. CLAY OCCURRENCES 4. 'THE GRAVEL 5. MAMMALIAN REMAINS 6. CORRELATION OF GRAVEL
41 41 43 44 45 46 46
ACKNOWLEDGMENTS REFERENCES
ABSTRACT: Patches of Jurassic river gravel near Bourton-on-the-Water, Glos, in the basin of the Windrush, have yielded mammoth and woolly rhinoceros. In their upper parts they display features associated with freeze and thaw. There is evidence for identification with the older gravels of the Summertown-Radley Terrace around Oxford and for recognising the stage from the headwaters of the Windrush to its confluence with the Upper Thames. Fact s a re given concerning bodies of clay in the gravel-bed , but their origin is ob scure.
1. INTRODUCfION Vale of Bourton are seven tracts of well-rolled limestone (or Jurassic) gravels, the boundaries of which are shown approximately on the Geological Survey maps, Sheets 217 (Drift) and 235 (Drift). Five of these tracts are in the northern part of the Vale in advance of where the Rivers Windrush, Eye (better known locally as the Slaughter Brook) and Dikler flow out of the hill country on to the, by comparison, low ground of the Vale. As would be expected, the gravel is composed almost entirely of pebbles of Inferior and Great Oolite limestones, the very small residue being of Liassic limestone, all of which were brought down by the rivers named. Great Chessells Gravel Pit is situated on the north side of the Fosse Way immediately west of the Dikler at Stow Bridge between Stow-on-the-Wold and Bourton-on-the-Water. The original part of the pit, now worked out, was called Little Chessells Gravel Pit : the present vast pit is Great Chessells or Farnworth's Gravel Pit, after the name of the owner, Mr. L. J. Farnworth. IN THE
40
MAMMALIAN REMAINS IN GLOUCESTERSHIRE
41
The pit has been kept under observation by Mrs. Helen O'Neil, F.S.A., for archaeological reasons, for over five-and-twenty years, and she has been rewarded by discoveries of great interest. It is very evident that this gravel tract was an occupation site during Romano-British times and possibly earlier. During this same period of over five-and-twenty years, ten molars of mammoth and four teeth of rhinoceros have been found and -except for one mammoth molar-have been presented to the University Museum, Oxford. 2. DESCRIPTION OF SECTION The following is a very brief description of the section; details follow: Surface-level. Maximum, c. 462 feet O.D. CLAY OCCURRENCES. LIMESTONE GRAVEL. Well
Thickness in feet rolled:
I. Festooned ('frozen soil gravel') with highly inclined
pebbles; no suggestion of soil: up to
3
2. Fore-set, with occasional lenses of ironstone pebbles and (a) of sandy clay, and (b) of oolith 'sand'. The teeth of mammoth and rhinoceros are said to have occurred consistently at the bottom of the face, i.e, at 9 or 10 feet above the Lower Lias: c. 10 - - - - - - - - - Pit floor, 1958- - - - - - 3. Bedded, with numerous layers of greenish-yellow sandy clay: c. ... 9 Lower Lias. Tough bluish-grey clay. Secondary lime-cementation occurs, but it is not extensive. Ramifying veins of lime and lime-cemented gravel traverse the face from top to bottom. The water-level fluctuates by five feet; but there is always a depth of two feet present, i.e. the maximum depth of water is seven feet.
The variation in depth of the present working-face is in accord with the contour of the ground. After the upper part of the gravel has been removed, it is contemplated removing the lower part, some nine feet thick; but, on account of its greater clay content, washing would probably be necessary. 3. CLAY OCCURRENCES The Clay Occurrences are in two forms: (I) roughly, as a spread on the surface of the gravel; and (2) in pits-the 'clay-pits' of the quarrymen. According to Mrs. O'Neil, the clay on the surface of the gravel is very generally distributed and reddish-brown in colour; but surface-appearances when seen by the authors indicated that much was blackish. The only place where the authors saw it clearly in section, capping the gravel, was along part of the western face of the pit. Here it is black and most likely the product of decalcification plus deep mixing of soil and organic matter due
42
L. RICHARDSON AND K. S. SANDFORD
to the lengthy occupation of the site in Romano-British times and possibly earlier. From this stretch of clay were collected some Roman sherds, fragments of ironstone slag, and three small Bunter pebbles, one of which showed clear signs of having been used as a rubber. The junction of clay and underlying gravel is irregular; but no pipes involving the clay were observed running down into the gravel. The ploughed fields on the limestones of the Cotswolds usually have a clayey soil, frequently reddish-brown on the Inferior Oolite, very sticky in wet weather. Mechanical analyses of six samples of soil on Inferior and Great Oolite limestones in the Cirencester district gave a silt-plus-clay percentage ranging from 44.7 to 56.2 (Hanley, in Richardson, 1933, 102). The Chessells gravel is pure limestone gravel (with the exception of ironstone pebbles, also derived from the local Inferior Oolite), devoid of quartzose sand, and, accordingly, very prone to decalcification. It has not been found possible to make a satisfactory suggestion as to the origin of the 'clay-pits', but it appears desirable to give such facts as have been obtained. An aerial photograph of the northern part of the gravel tract, the only part remaining unexploited at the time but now further reduced, showed a number of irregularly distributed white patches of various sizes and shapes. Mrs. O'Neil reports: 'We proved these white patches were "clay-pits" by watching three of them to see what happened.' These clay-pits have been encountered all over the gravel tract and occur in the upper part of the gravel. The largest was one of the three mentioned above. To quote Mrs. O'Neil (in litt., 16.9.58): 'Where I took the photograph it was thirty to forty feet across at the top. I did not measure the length as, of course, it was not uncovered all at once.' The clay was eight feet in depth and had normal gravel beneath. The clay of this pit had been removed from its position in the gravel by the time of the authors' first visit, but they were shown the 'tip' and were thus able to examine it. It was mostly reddish-brown; was not blackened by deep mixing of soil and organic matter due to occupation; and was devoid of fossils (which might have dated it, geologically) and fragments of pottery, bones and charcoal. According to Mrs. O'Neil (in litt., 11.9.58): 'These clay areas did not produce any finds, and, in fact, where any Romano-British hut or house site impinged on a clay-pit, the foundations of the hut or house were reinforced with extra stone revetments.' The clay contained, however, flattish pebbles of ironstone similar to those concentrated in the lenses in the gravel and sporadically distributed elsewhere. One medium-sized Bunter pebble was obtained from the clay. The last pit brought to light (August 1958) was examined by one of the authors (K.S.S.); but only to a depth of, say, two and a half feet, because evidence obtained appeared to indicate that the clay-pit was artificial, and,
PROC. GEOL. ASSOC., VOL. 71 (1960)
PLATE 4
Photo: Mrs. Helen O'Neil
One of the many lime-pipes in the gravel at Great Chessells Gravel Pit [To jace p. 42
MAMMALIAN REMAINS IN GLOUCESTERSHIRE
43
consequently, the concern of the archaeologist rather than the geologist. It was about eight feet in diameter and the junction of clay and gravel was sharp. At about twofeet down someflat slabs oflimestone were encountered, beneath which was similar clay again. In the top of this clay, just beneath the limestone slabs, a piece of red pottery and a flint were found. Mrs. O'Neil has pronounced the pottery Roman; and the flint a chip off a pebble-not an artefact. Concerning this last clay-pit, Mrs. O'Neil remarks that it certainly does seem to have a very clear-cut edge; but adds that the enormous clay-pits she had previously reported were certainly natural. One of the authors (L.R.) favours the opinion that the clay-pits are natural, but is unable to make a satisfactory suggestion as to their origin. It is noteworthy that the clay lacks the blackish colour and archaeological contents due to the occupation of the site. It contains, however, numerous flattish ironstone pebbles similar to those in the gravel-bed. It may be recalled that in clay occurrences in gravel acknowledged to be the product of decalcification the limestone pebbles have been removed, while those of ironstone have survived.
4. THE GRAVEL The gravel, as has been already stated, is limestone gravel composed almost entirely of pebbles made of rock derived from the Inferior and Great Oolites of the neighbouring hills. Flattish pebbles of the sandy form of Cotswold (or Stonesfield) Slate are numerous. So far as is known the Stonesfield Slate beds do not occur in the hills bordering the Dikler valley in the neighbourhood of the Swells,but they are present and well developed in the hills west of Upper Slaughter and on Eyford Hill on the west side of the River Eye. Pebbles of bluish-grey Lias limestone occur, but are few. Those of ironstone, however, are frequent, and largely compose lenses in the Fore-set Gravel. On account of their black colour they quickly catch the eye. These ironstone pebbles, mostly on the flattish side, were doubtless derived from such 'Very ferruginous ... beds, full of ossicles of Isocrinus .and fragments of echinoid radioles', as constitute the top part of the PeaGrit Series Equivalent in the-now long-disused-Town Quarry near Copse Hill House, a mile or so to the north-west of Chessells (Richardson, 1929,60). The Festooned Gravel (1 of section, p. 41) includes a considerable amount of marly matter, the result of decalcification-a process still active. The Fore-set part of the gravel deposit contains occasional lenses of (a) greenish-yellow clay with an admixture of fine-grained sand, and (b) of 'sand', not quartzose, but composed entirely of loose ooliths. No freshwater shells have been detected in the clay lenses. The Bedded Gravel has not yet been worked in this pit, but it has been
44
L. RICHARDSON AND K. S. SANDFORD
partly exposed in a trial trench and is still well-exposed in Young's old gravel-pit adjoining Chessells on the south-west and now owned by Mr. A. T. Wheeler of Lower Slaughter. This Bedded Gravel has numerous layers of greenish-yellow sandy clay intercalated. Secondary lime-cementation of the gravel has been observed in most of the pits once open in the neighbourhood; but it is not much in evidence in the part of the gravel exposed in this pit. Ramifying veins of lime and lime-cemented gravel locally descend the working-face from top to bottom and are more recent than the festooning of gravel. A feature of the eastern face, which is much lower than the western owing to the slope of the ground towards the Dikler, is the number of pipes that in vertical section give the impression of being thin partitions of gravel in the main mass. Their sides are plumb and apparently devoid of clay lining, are up to four inches in diameter, and have their contained pebbles with their longer axes vertical. In places as noticed by Dines (in Richardson, 1946, 114) in the case of pipes in the terrace at Long Hanborough, the bedding adjacent the pipe is, in places, turned upwards. No pipes, such as those that make so marked a feature of the Hanborough Terrace, have been developed in the Chessells gravel. Pebbles of rock foreign to the district are extremely rare in the gravel: A. E. Salter failed to find any (Salter, 1905, 37), and Mrs. O'Neil has only come across one small one-a 'Bunter' pebble. She has never found a flint in the gravel; but, on the occasion of a visit of the Geologists' Association to one of the local pits in 1904, at a time when it was customary to search most carefully for flints in the Cotswold limestone-gravels, one small piece was found in situ (Richardson, 1904, 412). 5. MAMMALIAN REMAINS The only previously published records of mammalian remains from the Vale of Bourton are by W. C. Lucy (1869, 123) and C. I. Gardiner (1939, 329).Lucy's record is a 'Tusk from near Bourton-on-the-Water'. Gardiner's records are a tooth of rhinoceros and three teeth of mammoth (identified by one of us (K.S.S.) as 'essentially of the Elephas primigenius stock', now in the Stroud Museum) from the now-disused Young's Gravel Pit; and one of mammoth from a pit nearer Bourton-by the side of the road to Bourton shortly after it has left the Fosse Way. In the Gloucester Museum are two specimens of Elephas primigenius, the one from Great Chessells Gravel Pit (Reg. No. 107/1957); and the other (16,881) found when sinking a well in the gravel-bed in Church Field, Bourton-on-the-Water, in 1910. The nine mammoth teeth from the Great Chessells Gravel Pit in the University Museum, Oxford, may be described summarily as follows. One
MAMMALIAN REMAINS IN GLOUCESTERSHIRE
45
has a black-mottled white outer surface and came, probably, from a dist inctive bed in the gravel, the remainder have almost identical yellowish and yellowish-brown surfaces: recent fractures are white. Four upper and three lower molars are represented, but none is complete. One specimen is probably part of an ultimate molar, the rest are probably later milk molars and early molars. The lamellae have notably strong, rather thick, crimped enamel and interlamellar cement is well developed (a condition which is variable with the height and other conditions of the tooth). Lamellar frequency (i.e. the number of plates within 100 mm.) is about ten. No tooth is complete enough for the lamellar ratio to be assessed with any satisfaction. In their features, however, the teeth are certainly like those of Elephas primigenius known from the Summertown-Radley gravels around Oxford (Sandford, 1925), and unlike those from the later, Flood Plain, gravels there. Three distinctive upper molars , and one lower molar, may be referred to the woolly rhinoceros (Rhinoceros tichorhinus), and they have the same external coloration as the mammoth teeth [K.S.S.]. 6. CORRELATION OF GRAVEL The gravels described in this paper are isolated in the headwaters of a tributary of the Windrush. Farther downstream the main river flows in a spectacular Cotswold valley almost entirely lacking patches of old gravels, though the well-known abandoned meander and prominent meander-core at Asthall indicate a stage of valley deepening. The morphological features of the basin within the Cotswolds have been described by Beckinsale & Smith (1953), and it is hoped that further work will be done on the benches within the main valley as far as Witney. Here the Windrush passes on to the Oxford Clay plain and its gravels (with those of the adjacent Upper Thames) are widespread (Pringle & others , 1926; Richardson & others, 1946). Those referred to the Summertown-Radley terrace around Oxford (Sandford, in Pringle & others, 1926) predominate and contain mammoth and woolly rhinoceros: an upper, unconformable series seen locally upon them contain a fauna characterised by hippopotamus and Elephas antiquus. Frost-disturbed layers occur there near the top of whichever gravel forms the terrace-surface, i.e. the disturbed condition may have been attained either after the lower (mammoth) gravels were formed or during a cold period after the upper (hippopotamus) beds were formed . The geology of the deposits indicates that the latter is correct, but it is not to be assumed that there was only one such time of disturbance. In the writer's experience similar features do not occur on the superficial part of the Flood Plain gravels. Though the gravels of Great Chcssells form a clearly marked terrace
46
L. RICHARDSON AND K. S. SANDFORD
feature beside the Dikler, their base is but little above it, and probably, as in some places around Oxford, thickening occurs toward the stream. In their disposition they recall the gravels of the Summertown-Radley stage: the only fauna associated with them-and that derived from their upper part-is that of mammoth: the disturbance of their uppermost part is two-fold (p. 44), and hippopotamus-gravels are lacking. It is considered, therefore, that the stage is represented in the Windrush basin from the headwaters, through the Asthall meander, to the confluence with the Upper Thames [K.S.S.].
ACKNOWLEDGMENTS The 'finds' both archaeological and geological are largely due to the active co-operation of Mrs. O'Neil, Messrs. T. 0., L. J. and T. Farnworth and the quarrymen, particularly Mr. C. L. Holford. Geological circles are indebted to Mrs. O'Neil for collecting, preserving and eventually handing over the teeth for study and safe keeping. We would also record our thanks to Dr. R. P. Beckinsale for much help during our investigations.
REFERENCES BECKINSALE, R. P. & K. W. SMITH. 1955. Some Morphological Features of the Valleys of the North Cotswolds: The Windrush and its Tributaries. Proc, Cotteswold Nat. F1d CI., 31, 184-95. GARDINER, C. I. 1939. Rhinoceros Tooth. Proc. Cotteswold Nat. Fld CI., 26, 329. Lucy, W. C. 1869. The Gravels of the Severn, Avon and Evenlode, and their Extension over the Cotteswold Hills. Proc, Cotteswold Nat. Fld CI. 5,71-125. PRINGLE, J., et al. 1926. The Geology of the Country around Oxford (2nd ed.), Mem, geol. Surv. U.K. RICHARDSON, L. 1904. Excursion to ... the North Cotteswolds. Proc, Geol, Ass., Lond., 18, 391-408. - - - et al. 1929. The Country around Moreton-in-Marsh. Mem. geol, Surv. U.K. - - - et al. 1933. The Country around Cirencester. Mem. geol. Surv. U.K. - - - et al. 1946. The Geology of the Country around Witney. Mem. geol. Surv. U.K. SALTER, A. E. 1905. On the Superficial Deposits of Central and Parts of Southern England. Proc. Geol. Ass., Lond., 19. SANDFORD, K. S. 1925. The Fossil Elephants of the Upper Thames Basin. Quart. J. geol. Soc. Lond., 81, 62-86.
CONTENTS page 40
1. INTRODUCTION 2. DESCRIPTION OF SECTION 3. CLAY OCCURRENCES 4. 'THE GRAVEL 5. MAMMALIAN REMAINS 6. CORRELATION OF GRAVEL
41 41 43 44 45 46 46
ACKNOWLEDGMENTS REFERENCES
ABSTRACT: Patches of Jurassic river gravel near Bourton-on-the-Water, Glos, in the basin of the Windrush, have yielded mammoth and woolly rhinoceros. In their upper parts they display features associated with freeze and thaw. There is evidence for identification with the older gravels of the Summertown-Radley Terrace around Oxford and for recognising the stage from the headwaters of the Windrush to its confluence with the Upper Thames. Fact s a re given concerning bodies of clay in the gravel-bed , but their origin is ob scure.
1. INTRODUCfION Vale of Bourton are seven tracts of well-rolled limestone (or Jurassic) gravels, the boundaries of which are shown approximately on the Geological Survey maps, Sheets 217 (Drift) and 235 (Drift). Five of these tracts are in the northern part of the Vale in advance of where the Rivers Windrush, Eye (better known locally as the Slaughter Brook) and Dikler flow out of the hill country on to the, by comparison, low ground of the Vale. As would be expected, the gravel is composed almost entirely of pebbles of Inferior and Great Oolite limestones, the very small residue being of Liassic limestone, all of which were brought down by the rivers named. Great Chessells Gravel Pit is situated on the north side of the Fosse Way immediately west of the Dikler at Stow Bridge between Stow-on-the-Wold and Bourton-on-the-Water. The original part of the pit, now worked out, was called Little Chessells Gravel Pit : the present vast pit is Great Chessells or Farnworth's Gravel Pit, after the name of the owner, Mr. L. J. Farnworth. IN THE
40
MAMMALIAN REMAINS IN GLOUCESTERSHIRE
41
The pit has been kept under observation by Mrs. Helen O'Neil, F.S.A., for archaeological reasons, for over five-and-twenty years, and she has been rewarded by discoveries of great interest. It is very evident that this gravel tract was an occupation site during Romano-British times and possibly earlier. During this same period of over five-and-twenty years, ten molars of mammoth and four teeth of rhinoceros have been found and -except for one mammoth molar-have been presented to the University Museum, Oxford. 2. DESCRIPTION OF SECTION The following is a very brief description of the section; details follow: Surface-level. Maximum, c. 462 feet O.D. CLAY OCCURRENCES. LIMESTONE GRAVEL. Well
Thickness in feet rolled:
I. Festooned ('frozen soil gravel') with highly inclined
pebbles; no suggestion of soil: up to
3
2. Fore-set, with occasional lenses of ironstone pebbles and (a) of sandy clay, and (b) of oolith 'sand'. The teeth of mammoth and rhinoceros are said to have occurred consistently at the bottom of the face, i.e, at 9 or 10 feet above the Lower Lias: c. 10 - - - - - - - - - Pit floor, 1958- - - - - - 3. Bedded, with numerous layers of greenish-yellow sandy clay: c. ... 9 Lower Lias. Tough bluish-grey clay. Secondary lime-cementation occurs, but it is not extensive. Ramifying veins of lime and lime-cemented gravel traverse the face from top to bottom. The water-level fluctuates by five feet; but there is always a depth of two feet present, i.e. the maximum depth of water is seven feet.
The variation in depth of the present working-face is in accord with the contour of the ground. After the upper part of the gravel has been removed, it is contemplated removing the lower part, some nine feet thick; but, on account of its greater clay content, washing would probably be necessary. 3. CLAY OCCURRENCES The Clay Occurrences are in two forms: (I) roughly, as a spread on the surface of the gravel; and (2) in pits-the 'clay-pits' of the quarrymen. According to Mrs. O'Neil, the clay on the surface of the gravel is very generally distributed and reddish-brown in colour; but surface-appearances when seen by the authors indicated that much was blackish. The only place where the authors saw it clearly in section, capping the gravel, was along part of the western face of the pit. Here it is black and most likely the product of decalcification plus deep mixing of soil and organic matter due
42
L. RICHARDSON AND K. S. SANDFORD
to the lengthy occupation of the site in Romano-British times and possibly earlier. From this stretch of clay were collected some Roman sherds, fragments of ironstone slag, and three small Bunter pebbles, one of which showed clear signs of having been used as a rubber. The junction of clay and underlying gravel is irregular; but no pipes involving the clay were observed running down into the gravel. The ploughed fields on the limestones of the Cotswolds usually have a clayey soil, frequently reddish-brown on the Inferior Oolite, very sticky in wet weather. Mechanical analyses of six samples of soil on Inferior and Great Oolite limestones in the Cirencester district gave a silt-plus-clay percentage ranging from 44.7 to 56.2 (Hanley, in Richardson, 1933, 102). The Chessells gravel is pure limestone gravel (with the exception of ironstone pebbles, also derived from the local Inferior Oolite), devoid of quartzose sand, and, accordingly, very prone to decalcification. It has not been found possible to make a satisfactory suggestion as to the origin of the 'clay-pits', but it appears desirable to give such facts as have been obtained. An aerial photograph of the northern part of the gravel tract, the only part remaining unexploited at the time but now further reduced, showed a number of irregularly distributed white patches of various sizes and shapes. Mrs. O'Neil reports: 'We proved these white patches were "clay-pits" by watching three of them to see what happened.' These clay-pits have been encountered all over the gravel tract and occur in the upper part of the gravel. The largest was one of the three mentioned above. To quote Mrs. O'Neil (in litt., 16.9.58): 'Where I took the photograph it was thirty to forty feet across at the top. I did not measure the length as, of course, it was not uncovered all at once.' The clay was eight feet in depth and had normal gravel beneath. The clay of this pit had been removed from its position in the gravel by the time of the authors' first visit, but they were shown the 'tip' and were thus able to examine it. It was mostly reddish-brown; was not blackened by deep mixing of soil and organic matter due to occupation; and was devoid of fossils (which might have dated it, geologically) and fragments of pottery, bones and charcoal. According to Mrs. O'Neil (in litt., 11.9.58): 'These clay areas did not produce any finds, and, in fact, where any Romano-British hut or house site impinged on a clay-pit, the foundations of the hut or house were reinforced with extra stone revetments.' The clay contained, however, flattish pebbles of ironstone similar to those concentrated in the lenses in the gravel and sporadically distributed elsewhere. One medium-sized Bunter pebble was obtained from the clay. The last pit brought to light (August 1958) was examined by one of the authors (K.S.S.); but only to a depth of, say, two and a half feet, because evidence obtained appeared to indicate that the clay-pit was artificial, and,
PROC. GEOL. ASSOC., VOL. 71 (1960)
PLATE 4
Photo: Mrs. Helen O'Neil
One of the many lime-pipes in the gravel at Great Chessells Gravel Pit [To jace p. 42
MAMMALIAN REMAINS IN GLOUCESTERSHIRE
43
consequently, the concern of the archaeologist rather than the geologist. It was about eight feet in diameter and the junction of clay and gravel was sharp. At about twofeet down someflat slabs oflimestone were encountered, beneath which was similar clay again. In the top of this clay, just beneath the limestone slabs, a piece of red pottery and a flint were found. Mrs. O'Neil has pronounced the pottery Roman; and the flint a chip off a pebble-not an artefact. Concerning this last clay-pit, Mrs. O'Neil remarks that it certainly does seem to have a very clear-cut edge; but adds that the enormous clay-pits she had previously reported were certainly natural. One of the authors (L.R.) favours the opinion that the clay-pits are natural, but is unable to make a satisfactory suggestion as to their origin. It is noteworthy that the clay lacks the blackish colour and archaeological contents due to the occupation of the site. It contains, however, numerous flattish ironstone pebbles similar to those in the gravel-bed. It may be recalled that in clay occurrences in gravel acknowledged to be the product of decalcification the limestone pebbles have been removed, while those of ironstone have survived.
4. THE GRAVEL The gravel, as has been already stated, is limestone gravel composed almost entirely of pebbles made of rock derived from the Inferior and Great Oolites of the neighbouring hills. Flattish pebbles of the sandy form of Cotswold (or Stonesfield) Slate are numerous. So far as is known the Stonesfield Slate beds do not occur in the hills bordering the Dikler valley in the neighbourhood of the Swells,but they are present and well developed in the hills west of Upper Slaughter and on Eyford Hill on the west side of the River Eye. Pebbles of bluish-grey Lias limestone occur, but are few. Those of ironstone, however, are frequent, and largely compose lenses in the Fore-set Gravel. On account of their black colour they quickly catch the eye. These ironstone pebbles, mostly on the flattish side, were doubtless derived from such 'Very ferruginous ... beds, full of ossicles of Isocrinus .and fragments of echinoid radioles', as constitute the top part of the PeaGrit Series Equivalent in the-now long-disused-Town Quarry near Copse Hill House, a mile or so to the north-west of Chessells (Richardson, 1929,60). The Festooned Gravel (1 of section, p. 41) includes a considerable amount of marly matter, the result of decalcification-a process still active. The Fore-set part of the gravel deposit contains occasional lenses of (a) greenish-yellow clay with an admixture of fine-grained sand, and (b) of 'sand', not quartzose, but composed entirely of loose ooliths. No freshwater shells have been detected in the clay lenses. The Bedded Gravel has not yet been worked in this pit, but it has been
44
L. RICHARDSON AND K. S. SANDFORD
partly exposed in a trial trench and is still well-exposed in Young's old gravel-pit adjoining Chessells on the south-west and now owned by Mr. A. T. Wheeler of Lower Slaughter. This Bedded Gravel has numerous layers of greenish-yellow sandy clay intercalated. Secondary lime-cementation of the gravel has been observed in most of the pits once open in the neighbourhood; but it is not much in evidence in the part of the gravel exposed in this pit. Ramifying veins of lime and lime-cemented gravel locally descend the working-face from top to bottom and are more recent than the festooning of gravel. A feature of the eastern face, which is much lower than the western owing to the slope of the ground towards the Dikler, is the number of pipes that in vertical section give the impression of being thin partitions of gravel in the main mass. Their sides are plumb and apparently devoid of clay lining, are up to four inches in diameter, and have their contained pebbles with their longer axes vertical. In places as noticed by Dines (in Richardson, 1946, 114) in the case of pipes in the terrace at Long Hanborough, the bedding adjacent the pipe is, in places, turned upwards. No pipes, such as those that make so marked a feature of the Hanborough Terrace, have been developed in the Chessells gravel. Pebbles of rock foreign to the district are extremely rare in the gravel: A. E. Salter failed to find any (Salter, 1905, 37), and Mrs. O'Neil has only come across one small one-a 'Bunter' pebble. She has never found a flint in the gravel; but, on the occasion of a visit of the Geologists' Association to one of the local pits in 1904, at a time when it was customary to search most carefully for flints in the Cotswold limestone-gravels, one small piece was found in situ (Richardson, 1904, 412). 5. MAMMALIAN REMAINS The only previously published records of mammalian remains from the Vale of Bourton are by W. C. Lucy (1869, 123) and C. I. Gardiner (1939, 329).Lucy's record is a 'Tusk from near Bourton-on-the-Water'. Gardiner's records are a tooth of rhinoceros and three teeth of mammoth (identified by one of us (K.S.S.) as 'essentially of the Elephas primigenius stock', now in the Stroud Museum) from the now-disused Young's Gravel Pit; and one of mammoth from a pit nearer Bourton-by the side of the road to Bourton shortly after it has left the Fosse Way. In the Gloucester Museum are two specimens of Elephas primigenius, the one from Great Chessells Gravel Pit (Reg. No. 107/1957); and the other (16,881) found when sinking a well in the gravel-bed in Church Field, Bourton-on-the-Water, in 1910. The nine mammoth teeth from the Great Chessells Gravel Pit in the University Museum, Oxford, may be described summarily as follows. One
MAMMALIAN REMAINS IN GLOUCESTERSHIRE
45
has a black-mottled white outer surface and came, probably, from a dist inctive bed in the gravel, the remainder have almost identical yellowish and yellowish-brown surfaces: recent fractures are white. Four upper and three lower molars are represented, but none is complete. One specimen is probably part of an ultimate molar, the rest are probably later milk molars and early molars. The lamellae have notably strong, rather thick, crimped enamel and interlamellar cement is well developed (a condition which is variable with the height and other conditions of the tooth). Lamellar frequency (i.e. the number of plates within 100 mm.) is about ten. No tooth is complete enough for the lamellar ratio to be assessed with any satisfaction. In their features, however, the teeth are certainly like those of Elephas primigenius known from the Summertown-Radley gravels around Oxford (Sandford, 1925), and unlike those from the later, Flood Plain, gravels there. Three distinctive upper molars , and one lower molar, may be referred to the woolly rhinoceros (Rhinoceros tichorhinus), and they have the same external coloration as the mammoth teeth [K.S.S.]. 6. CORRELATION OF GRAVEL The gravels described in this paper are isolated in the headwaters of a tributary of the Windrush. Farther downstream the main river flows in a spectacular Cotswold valley almost entirely lacking patches of old gravels, though the well-known abandoned meander and prominent meander-core at Asthall indicate a stage of valley deepening. The morphological features of the basin within the Cotswolds have been described by Beckinsale & Smith (1953), and it is hoped that further work will be done on the benches within the main valley as far as Witney. Here the Windrush passes on to the Oxford Clay plain and its gravels (with those of the adjacent Upper Thames) are widespread (Pringle & others , 1926; Richardson & others, 1946). Those referred to the Summertown-Radley terrace around Oxford (Sandford, in Pringle & others, 1926) predominate and contain mammoth and woolly rhinoceros: an upper, unconformable series seen locally upon them contain a fauna characterised by hippopotamus and Elephas antiquus. Frost-disturbed layers occur there near the top of whichever gravel forms the terrace-surface, i.e. the disturbed condition may have been attained either after the lower (mammoth) gravels were formed or during a cold period after the upper (hippopotamus) beds were formed . The geology of the deposits indicates that the latter is correct, but it is not to be assumed that there was only one such time of disturbance. In the writer's experience similar features do not occur on the superficial part of the Flood Plain gravels. Though the gravels of Great Chcssells form a clearly marked terrace
46
L. RICHARDSON AND K. S. SANDFORD
feature beside the Dikler, their base is but little above it, and probably, as in some places around Oxford, thickening occurs toward the stream. In their disposition they recall the gravels of the Summertown-Radley stage: the only fauna associated with them-and that derived from their upper part-is that of mammoth: the disturbance of their uppermost part is two-fold (p. 44), and hippopotamus-gravels are lacking. It is considered, therefore, that the stage is represented in the Windrush basin from the headwaters, through the Asthall meander, to the confluence with the Upper Thames [K.S.S.].
ACKNOWLEDGMENTS The 'finds' both archaeological and geological are largely due to the active co-operation of Mrs. O'Neil, Messrs. T. 0., L. J. and T. Farnworth and the quarrymen, particularly Mr. C. L. Holford. Geological circles are indebted to Mrs. O'Neil for collecting, preserving and eventually handing over the teeth for study and safe keeping. We would also record our thanks to Dr. R. P. Beckinsale for much help during our investigations.
REFERENCES BECKINSALE, R. P. & K. W. SMITH. 1955. Some Morphological Features of the Valleys of the North Cotswolds: The Windrush and its Tributaries. Proc, Cotteswold Nat. F1d CI., 31, 184-95. GARDINER, C. I. 1939. Rhinoceros Tooth. Proc. Cotteswold Nat. Fld CI., 26, 329. Lucy, W. C. 1869. The Gravels of the Severn, Avon and Evenlode, and their Extension over the Cotteswold Hills. Proc, Cotteswold Nat. Fld CI. 5,71-125. PRINGLE, J., et al. 1926. The Geology of the Country around Oxford (2nd ed.), Mem, geol. Surv. U.K. RICHARDSON, L. 1904. Excursion to ... the North Cotteswolds. Proc, Geol, Ass., Lond., 18, 391-408. - - - et al. 1929. The Country around Moreton-in-Marsh. Mem. geol, Surv. U.K. - - - et al. 1933. The Country around Cirencester. Mem. geol. Surv. U.K. - - - et al. 1946. The Geology of the Country around Witney. Mem. geol. Surv. U.K. SALTER, A. E. 1905. On the Superficial Deposits of Central and Parts of Southern England. Proc. Geol. Ass., Lond., 19. SANDFORD, K. S. 1925. The Fossil Elephants of the Upper Thames Basin. Quart. J. geol. Soc. Lond., 81, 62-86.