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Field Meeting at Swanscombe, kent
357 FIELD MEETING AT SWANSCOMBE, KENT. Saturday, March 25th, 1939. R eport by the Director: K. P . OAKLEY, B.Sc., Ph.D., F .G.S.
THE principal object of the Meeting was to give members an opportunity of studying the fine sections in the deposits of the roo-ft. Terrace of the Lower Thames which a re available in the Barnfield Pit at Swanscombe. A party of about forty members and their friend s assembled in the pit at 2 .30 p.m. By way of introduction th e Direct or gave an account of the earlier Pleistocene history of the Th am es. He referred to Dr. S. W. Wooldridge's conclusion that th e Early Pleistocene Thames, after passing through the Goring Gap , had flowed north-eastwards to the North Sea through the region of Ware in Hertfordshire. It had seemingly been div ert ed from this course to its present one (through the region in which Swanscombe lay) by the Lower Chalky Boulder Clay glaciation. Thus the Lower Chalky Boulder Clay appeared t o provid e a terminus ante quem for the commencement of deposition on the roo-ft. Terrace in the present Lower Thames valley. The erratics in the gravels of the roo-ft. Terrace supported thi s conclusion in so far as they includ ed und oubted derivatives from a boulder clay of Chalky-Jurassic facies. It mu st be admitted that this Lower Chalky Bould er Clay may prove t o represent a phase of the glaciation which formed th e ?-' orth Sea Drift of the East Anglian coast. The deposition of the fluviatile gra vels of th e l oa-ft . Terrace took place under interglacial conditions. The cold period to which these gave pla ce was marked in the Lower Thames valley by the Main Coombe Rock, a periglacial equivalent of the main Upper Chalky Boulder Clay of East Anglia. The Director demonstrated th e succession in th e Barnfield Pit. He explained that in th e Swanscombe area th e deposits of the roo-ft. Terrace were contained by a broad channel trending west to east , roughly par allel with th e course of t he present river. The northern bank of this channel was cut in Chalk, the southern bank in Thanet Sand. The floor of the channel in its deepest part was about 75 ft. above O.D. The surface of the deposits based in this channel attained a height of lIS ft. above a.D. In the Barnfield Pit the deposits exhibited a fairly uniform stratification and the local divisions recognised by Messrs. Smith and Dewey in 1913 still held good: Lower Gravel, Lower Loam, Middle Gravels and Sands, Upper Loam and Upper Gravel. The deposits up to, and including, the Upper Loam were of fluviatile origin , but the Upper Gravel (which passed locally
358
K. P. OAKLEY,
into a brown, stony clay) was a solifluxion deposit, presumed to be equivalent to the Main Coombe Rock of Northfleet. The Lower Gravel had yielded an abundant mammalian fauna, mainly of forest type, including such forms as Elephas antiquus, Dama clactoniana (Cervus browni auctt.) and Rhinoceros megarhinus (R. merckii auctt.). A shell-bed occurred near the top of this division. The Lower Loam was a flood deposit (Auelehm) and contained shells of freshwater and land mollusca, the latter predominating towards the top. In the Middle Gravels mammalian remains were less abundant and more scrappy, but it was in this division that Mr. A. T. Marston had found the fragments of the now famous Swanscombe Skull. The mammalian fauna of the Middle Gravels was still imperfectly known, but it included Elephas antiquus together with what appeared to be an early variety of E. primigenius. Bovine, deer, and horse remains also occurred. Recently an antler referable to Giant Deer (M egaceros) had been recovered. Impersistent shell-beds were found in the Middle Gravels, and it was interesting to note that the land shells in this division gave rather more evidence of grassland than those in the Lower Gravel or Lower Loam. It was worth recording that Gryphaea shells, derived from a Chalky-Jurassic boulder clay, had now been found in both Lower and Middle Gravels in the Barnfield Pit. The Director next dealt with the archseological succession in the pit. The Lower Gravel abounded in roughly trimmed flakes and cores. These had originally been referred to as " Strepyian ? " but they were now recognised as representing a typical Early Clactonian industry. The Lower Gravel industry was less advanced in character than the type Clactonian industry found in the fluviatile gravels which occupied the old channel of the Thames at Clacton-on-Sea, in Essex. In the lower part of the Barnfield Middle Gravels, however, Clactonian flakes showing more evolved technique than those of the type industry had been found. This was part of the evidence which indicated that between the deposition of the Barnfield Lower Gravel and Loam, and the deposition of the Middle Gravels, the river had abandoned the Swanscornbe channel, and had cut and aggraded a ' sunk channel' analogous to the well-known Buried Channel of later times. Sections of this ancient ' sunk channel' were preserved, not only at Clacton-on-Sea (where it extended to below present sea level), but also in the present valley, as at Grays (where its base was estimated to be 20 ft. above a.D.). The fact that the surface of the Lower Loam in the Barnfield Pit was weathered and had the characters of a fossil soil was cited as further support for the postulated hiatus in deposition on the roo-ft. Terrace, corresponding to the erosion and subsequent aggradation of the Clacton-Grays channel.
FIELD MEETING AT SWANSCOMBE, KENT.
359
The Middle Gravels of the Barnfield Pit were noted for their richness in paleeolithic hand-axes. The implements found in the Middle Gravels were originally styled" Chelles and Transition to St. Acheul," but all the contemporaneous hand-axes and many of the accompanying flake-tools from this division were now generally recognised as representing stages of a Middle Acheulian industry (the " Chellian " industry being earlier than any part of the IOO-ft. Terrace, and the Lower Acheulian being roughly contemporary with the Lower Gravel Clactonian). The Acheulian hand-axes in the Middle Gravels were accompanied by waste flakes, indicating that they had been manufactured close at hand, perhaps on gravelly shoals exposed when the river was low. After members had examined and collected from an exposure of Lower Gravel the Director demonstrated a section at the western extremity of the old working face. Here the deposits were seen to rest against a shelving bank of Thanet Sand which formed the southern margin of the Swanscombe channel. The party then returned to the part of the pit in which the deposits above the Lower Loam were being worked, and examined a section of Middle Gravels in the region of the site where the human skull had been found. It was possible to sub-divide the Middle Gravels of the Barnfield Pit into Lower Middle Gravels and Upper Middle Gravels and Sands. Mr. Marston had determined that the deposition of the upper group had been preceded by the cutting of a channel through the Lower Middle Gravel and locally down to the Lower Gravel. The occurrence of this channel might be used to illustrate an important principle involved in the building up of gravel spreads such as that on the IOO-ft. Terrace. An approximately graded river was continually shifting its course, cutting channels, filling them up, abandoning them and cutting new ones. Thus a terrace spread commonly consisted of a series intersecting, sand- and gravel-filled channels, and any particular bed of gravel was likely to be replaced laterally by another bed of slightly different age. For instance, the" Middle Gravels" of Rickson's Pit at Swanscombe probably occupied a secondary channel of slightly later date than that containing the Upper Middle Gravel of Barnfield Pit. The evidence for this suggestion lay in the fact that in the Middle Gravels of the Barnfield Pit hand-axes were mainly of the sharply pointed type, whereas in the "Middle Gravels" of Rickson's Pit such implements were accompanied by numerous examples of a later, ovate type.' r Since the appearance of the Report on the Swanscombe Skull ('938) Mr. Marston has found ovate hand-axes just below the Upper Loam in Colyer's Pit, perhaps indicating that the feather-edge of the Rickson's Pit" Middle Gravels" is represented above the Upper Middle Gravel, immediately north-east of the Barnfield pit.
K. P . OAKLEY,
The Director referred to NIr. Marsto n 's important discoveries in 1935 and 1936 of the occipital and left pariet al bones of a fossil human skull in the obliquely-bedded gravel which lined the channel within the Middle Gravels of Barnfield Pit. The fragm ents occurr ed in a ferru ginous seam about 24 ft. below the surface. They represented the first completely authenticated skull of Acheulian Man . According to Prof. Le Gros Clark and Dr. Morant it was difficult t o distinguish the bones act ually discovered from the corresponding bones in some skulls of H omo sapiens, whereas the same parts in all skulls of Homo neanderthalensis and other palreanthropic typ es (except that of Steinheim) could be readily so distinguished. The missing parts of the Swanscombe Skull might , however, have possessed features distinguishing it more definitely from skulls of modern t ype. Mr. Marston was pr esent and kindly consent ed t o give an account of his discov eries. H e exhibited a cast of the skull together with representative flint implements from the Middle Grave ls. From the act ual skull layer he had recovered half a dozen finely made Acheulian hand-axes, as well as over 7 0 0 waste flakes. H e stated his own views on the cultural succession and stra tigraphy of the l oa-ft . Terr ace. These differed from the views of t he Swan scombe Committee of the R oyal Anthropological In sti tute, as put forward during the afternoon by the Director. Mr. Marston considered th at the cha nelling within th e Middle Gravels represented a more importa nt hiat us than th at assumed to be marked by the weat hered surface of the Lower Loam , and he believed the hand-axe industry in th e Lower Middle Gravel t o be mu ch more primitive than that in the Upper Middle Gravel. H e considered that the Swanscombe calvaria was more primitive than that of Piltdown Man. The party next visited the excavat ion imm ediat ely ad joining the Barnfield Pit proper and nominally distinguished as Colyer's Pit.' Towards the north-western end of the working face the Lower Loam was here seen to be cut out by the Middle Grav els which thus rested dir ectly on th e Lower Gravel. Mr. A. S. Kenn ard, who had been in vestigatin g t he molluscan faun as of the Swan scombe Gravels on behalf of the Swanscombe Committee of the Royal Anthropological Institute, aided by a grant from the Royal Society, gave a brief account of his findings. He said that the mollu scan fauna of the part of the Lower Gravel now exposed was similar t o that of the Clact on gravels. It showed no relationship with the contemporaneous faun a of the Rhine, but could be mat ched closely in the High Terrace of the Sornme. The land shells in the Lower Gravel and Lower Loam indicated a forest environment . The mollu scan faun a of the Middle Gravels was very different, and showed clear affinities I
The two pits are now being worked as one by the Stone Court Ballast Co.
FIELD )IEETING AT SWANSCOMBE. KENT.
361
with that of the Middle Pleistocene Rhine. The land shells in the Middle Gravels appeared to give more evidence of grassland bordering the river than those in the Lower Gravel. Mr. Kennard considered that the shell-bed exposed in the Globe Pit at In gress Vale, near Greenhithe, had more in common with the shelly horizons in the Middle Gravels than with the shell-bed now exposed in the Lower Gravel, with which it had generally been correlated. Differences in age of shelly patches on apparently the same horizon were ' explained as being due to channelling such as that referred to in connexion with the Middle Gravels. The party proceeded to the Coopers Arms for tea, after which Mr. E . E. S. Brown , Vice-President, proposed a vote of thanks to the Director for conducting the Field Meeting, and to Messrs. Marston and Kennard for their interesting contributions. Some members accompanied the Director to a section near Baker's Hole, Northfleet, where, in spite of the failing light, they were able to examine typical coombe rock resting on the shelf of the 50-ft. Terrace. REFERENCES. D EWEY, H . AND SMITH, R . A. 1914 . The Pabeo lith ic Sequence at Swanscombe, Kent. Pro c. Geol . A ssoc., vol. xxv., pp. 90-97. D EWEY, H. , BROMEHEAD, C. E . N ., CHATWIN, C. P ., and DI NES, H . G . 1924 . The Geolo gy of the Cou n t ry a ro u nd Dartford . M elli. Geol, S urv. (Sheet 271). CHANDLER, R. H . 1930 . On the Clactonian Industry a t Swa nsco rnbe. P roc. Pr ehi st, So c. E. Anglia , v ol. vi ., pp. 79-1I6. DEWEY, H. 1932. The Palmolithic Dep osits of the L ow er T hames Valley. Quart. f ourn , Geol, Soc. , vol. lxxxviii., pp. 35-54. KING, \V. B. R ., and OAKLEY, K . P . 1936. The P leistocene Succession in the Lower parts of the Thames Va lley. P roc, P rehi si. S oc., n .s., vol. ii ., pp . 52-76. MARSTON, A. T . 193 8. The Swa nsco rnbe Skull. J our. R oy . A utbrop , Lnst. , v ol. lxvii. (1937), pp. 339-406. Swanscombe Com m it t ee R .A .I. 193 8. R eport on the Swanscombe Sk ull . Jou rn. Roy. A nthrop l nst., vol. lxviii , (1938) , pp. 17- 98. WOOLDRIDGE, S. W. 193 8. The Glaciation of the London Basin a nd the Evolution of the Lower Thames Draina ge Sy stem . Quart . Journ. Geol, Soc., vol. xciv ., pp. 627- 664.
THE principal object of the Meeting was to give members an opportunity of studying the fine sections in the deposits of the roo-ft. Terrace of the Lower Thames which a re available in the Barnfield Pit at Swanscombe. A party of about forty members and their friend s assembled in the pit at 2 .30 p.m. By way of introduction th e Direct or gave an account of the earlier Pleistocene history of the Th am es. He referred to Dr. S. W. Wooldridge's conclusion that th e Early Pleistocene Thames, after passing through the Goring Gap , had flowed north-eastwards to the North Sea through the region of Ware in Hertfordshire. It had seemingly been div ert ed from this course to its present one (through the region in which Swanscombe lay) by the Lower Chalky Boulder Clay glaciation. Thus the Lower Chalky Boulder Clay appeared t o provid e a terminus ante quem for the commencement of deposition on the roo-ft. Terrace in the present Lower Thames valley. The erratics in the gravels of the roo-ft. Terrace supported thi s conclusion in so far as they includ ed und oubted derivatives from a boulder clay of Chalky-Jurassic facies. It mu st be admitted that this Lower Chalky Bould er Clay may prove t o represent a phase of the glaciation which formed th e ?-' orth Sea Drift of the East Anglian coast. The deposition of the fluviatile gra vels of th e l oa-ft . Terrace took place under interglacial conditions. The cold period to which these gave pla ce was marked in the Lower Thames valley by the Main Coombe Rock, a periglacial equivalent of the main Upper Chalky Boulder Clay of East Anglia. The Director demonstrated th e succession in th e Barnfield Pit. He explained that in th e Swanscombe area th e deposits of the roo-ft. Terrace were contained by a broad channel trending west to east , roughly par allel with th e course of t he present river. The northern bank of this channel was cut in Chalk, the southern bank in Thanet Sand. The floor of the channel in its deepest part was about 75 ft. above O.D. The surface of the deposits based in this channel attained a height of lIS ft. above a.D. In the Barnfield Pit the deposits exhibited a fairly uniform stratification and the local divisions recognised by Messrs. Smith and Dewey in 1913 still held good: Lower Gravel, Lower Loam, Middle Gravels and Sands, Upper Loam and Upper Gravel. The deposits up to, and including, the Upper Loam were of fluviatile origin , but the Upper Gravel (which passed locally
358
K. P. OAKLEY,
into a brown, stony clay) was a solifluxion deposit, presumed to be equivalent to the Main Coombe Rock of Northfleet. The Lower Gravel had yielded an abundant mammalian fauna, mainly of forest type, including such forms as Elephas antiquus, Dama clactoniana (Cervus browni auctt.) and Rhinoceros megarhinus (R. merckii auctt.). A shell-bed occurred near the top of this division. The Lower Loam was a flood deposit (Auelehm) and contained shells of freshwater and land mollusca, the latter predominating towards the top. In the Middle Gravels mammalian remains were less abundant and more scrappy, but it was in this division that Mr. A. T. Marston had found the fragments of the now famous Swanscombe Skull. The mammalian fauna of the Middle Gravels was still imperfectly known, but it included Elephas antiquus together with what appeared to be an early variety of E. primigenius. Bovine, deer, and horse remains also occurred. Recently an antler referable to Giant Deer (M egaceros) had been recovered. Impersistent shell-beds were found in the Middle Gravels, and it was interesting to note that the land shells in this division gave rather more evidence of grassland than those in the Lower Gravel or Lower Loam. It was worth recording that Gryphaea shells, derived from a Chalky-Jurassic boulder clay, had now been found in both Lower and Middle Gravels in the Barnfield Pit. The Director next dealt with the archseological succession in the pit. The Lower Gravel abounded in roughly trimmed flakes and cores. These had originally been referred to as " Strepyian ? " but they were now recognised as representing a typical Early Clactonian industry. The Lower Gravel industry was less advanced in character than the type Clactonian industry found in the fluviatile gravels which occupied the old channel of the Thames at Clacton-on-Sea, in Essex. In the lower part of the Barnfield Middle Gravels, however, Clactonian flakes showing more evolved technique than those of the type industry had been found. This was part of the evidence which indicated that between the deposition of the Barnfield Lower Gravel and Loam, and the deposition of the Middle Gravels, the river had abandoned the Swanscornbe channel, and had cut and aggraded a ' sunk channel' analogous to the well-known Buried Channel of later times. Sections of this ancient ' sunk channel' were preserved, not only at Clacton-on-Sea (where it extended to below present sea level), but also in the present valley, as at Grays (where its base was estimated to be 20 ft. above a.D.). The fact that the surface of the Lower Loam in the Barnfield Pit was weathered and had the characters of a fossil soil was cited as further support for the postulated hiatus in deposition on the roo-ft. Terrace, corresponding to the erosion and subsequent aggradation of the Clacton-Grays channel.
FIELD MEETING AT SWANSCOMBE, KENT.
359
The Middle Gravels of the Barnfield Pit were noted for their richness in paleeolithic hand-axes. The implements found in the Middle Gravels were originally styled" Chelles and Transition to St. Acheul," but all the contemporaneous hand-axes and many of the accompanying flake-tools from this division were now generally recognised as representing stages of a Middle Acheulian industry (the " Chellian " industry being earlier than any part of the IOO-ft. Terrace, and the Lower Acheulian being roughly contemporary with the Lower Gravel Clactonian). The Acheulian hand-axes in the Middle Gravels were accompanied by waste flakes, indicating that they had been manufactured close at hand, perhaps on gravelly shoals exposed when the river was low. After members had examined and collected from an exposure of Lower Gravel the Director demonstrated a section at the western extremity of the old working face. Here the deposits were seen to rest against a shelving bank of Thanet Sand which formed the southern margin of the Swanscombe channel. The party then returned to the part of the pit in which the deposits above the Lower Loam were being worked, and examined a section of Middle Gravels in the region of the site where the human skull had been found. It was possible to sub-divide the Middle Gravels of the Barnfield Pit into Lower Middle Gravels and Upper Middle Gravels and Sands. Mr. Marston had determined that the deposition of the upper group had been preceded by the cutting of a channel through the Lower Middle Gravel and locally down to the Lower Gravel. The occurrence of this channel might be used to illustrate an important principle involved in the building up of gravel spreads such as that on the IOO-ft. Terrace. An approximately graded river was continually shifting its course, cutting channels, filling them up, abandoning them and cutting new ones. Thus a terrace spread commonly consisted of a series intersecting, sand- and gravel-filled channels, and any particular bed of gravel was likely to be replaced laterally by another bed of slightly different age. For instance, the" Middle Gravels" of Rickson's Pit at Swanscombe probably occupied a secondary channel of slightly later date than that containing the Upper Middle Gravel of Barnfield Pit. The evidence for this suggestion lay in the fact that in the Middle Gravels of the Barnfield Pit hand-axes were mainly of the sharply pointed type, whereas in the "Middle Gravels" of Rickson's Pit such implements were accompanied by numerous examples of a later, ovate type.' r Since the appearance of the Report on the Swanscombe Skull ('938) Mr. Marston has found ovate hand-axes just below the Upper Loam in Colyer's Pit, perhaps indicating that the feather-edge of the Rickson's Pit" Middle Gravels" is represented above the Upper Middle Gravel, immediately north-east of the Barnfield pit.
K. P . OAKLEY,
The Director referred to NIr. Marsto n 's important discoveries in 1935 and 1936 of the occipital and left pariet al bones of a fossil human skull in the obliquely-bedded gravel which lined the channel within the Middle Gravels of Barnfield Pit. The fragm ents occurr ed in a ferru ginous seam about 24 ft. below the surface. They represented the first completely authenticated skull of Acheulian Man . According to Prof. Le Gros Clark and Dr. Morant it was difficult t o distinguish the bones act ually discovered from the corresponding bones in some skulls of H omo sapiens, whereas the same parts in all skulls of Homo neanderthalensis and other palreanthropic typ es (except that of Steinheim) could be readily so distinguished. The missing parts of the Swanscombe Skull might , however, have possessed features distinguishing it more definitely from skulls of modern t ype. Mr. Marston was pr esent and kindly consent ed t o give an account of his discov eries. H e exhibited a cast of the skull together with representative flint implements from the Middle Grave ls. From the act ual skull layer he had recovered half a dozen finely made Acheulian hand-axes, as well as over 7 0 0 waste flakes. H e stated his own views on the cultural succession and stra tigraphy of the l oa-ft . Terr ace. These differed from the views of t he Swan scombe Committee of the R oyal Anthropological In sti tute, as put forward during the afternoon by the Director. Mr. Marston considered th at the cha nelling within th e Middle Gravels represented a more importa nt hiat us than th at assumed to be marked by the weat hered surface of the Lower Loam , and he believed the hand-axe industry in th e Lower Middle Gravel t o be mu ch more primitive than that in the Upper Middle Gravel. H e considered that the Swanscombe calvaria was more primitive than that of Piltdown Man. The party next visited the excavat ion imm ediat ely ad joining the Barnfield Pit proper and nominally distinguished as Colyer's Pit.' Towards the north-western end of the working face the Lower Loam was here seen to be cut out by the Middle Grav els which thus rested dir ectly on th e Lower Gravel. Mr. A. S. Kenn ard, who had been in vestigatin g t he molluscan faun as of the Swan scombe Gravels on behalf of the Swanscombe Committee of the Royal Anthropological Institute, aided by a grant from the Royal Society, gave a brief account of his findings. He said that the mollu scan fauna of the part of the Lower Gravel now exposed was similar t o that of the Clact on gravels. It showed no relationship with the contemporaneous faun a of the Rhine, but could be mat ched closely in the High Terrace of the Sornme. The land shells in the Lower Gravel and Lower Loam indicated a forest environment . The mollu scan faun a of the Middle Gravels was very different, and showed clear affinities I
The two pits are now being worked as one by the Stone Court Ballast Co.
FIELD )IEETING AT SWANSCOMBE. KENT.
361
with that of the Middle Pleistocene Rhine. The land shells in the Middle Gravels appeared to give more evidence of grassland bordering the river than those in the Lower Gravel. Mr. Kennard considered that the shell-bed exposed in the Globe Pit at In gress Vale, near Greenhithe, had more in common with the shelly horizons in the Middle Gravels than with the shell-bed now exposed in the Lower Gravel, with which it had generally been correlated. Differences in age of shelly patches on apparently the same horizon were ' explained as being due to channelling such as that referred to in connexion with the Middle Gravels. The party proceeded to the Coopers Arms for tea, after which Mr. E . E. S. Brown , Vice-President, proposed a vote of thanks to the Director for conducting the Field Meeting, and to Messrs. Marston and Kennard for their interesting contributions. Some members accompanied the Director to a section near Baker's Hole, Northfleet, where, in spite of the failing light, they were able to examine typical coombe rock resting on the shelf of the 50-ft. Terrace. REFERENCES. D EWEY, H . AND SMITH, R . A. 1914 . The Pabeo lith ic Sequence at Swanscombe, Kent. Pro c. Geol . A ssoc., vol. xxv., pp. 90-97. D EWEY, H. , BROMEHEAD, C. E . N ., CHATWIN, C. P ., and DI NES, H . G . 1924 . The Geolo gy of the Cou n t ry a ro u nd Dartford . M elli. Geol, S urv. (Sheet 271). CHANDLER, R. H . 1930 . On the Clactonian Industry a t Swa nsco rnbe. P roc. Pr ehi st, So c. E. Anglia , v ol. vi ., pp. 79-1I6. DEWEY, H. 1932. The Palmolithic Dep osits of the L ow er T hames Valley. Quart. f ourn , Geol, Soc. , vol. lxxxviii., pp. 35-54. KING, \V. B. R ., and OAKLEY, K . P . 1936. The P leistocene Succession in the Lower parts of the Thames Va lley. P roc, P rehi si. S oc., n .s., vol. ii ., pp . 52-76. MARSTON, A. T . 193 8. The Swa nsco rnbe Skull. J our. R oy . A utbrop , Lnst. , v ol. lxvii. (1937), pp. 339-406. Swanscombe Com m it t ee R .A .I. 193 8. R eport on the Swanscombe Sk ull . Jou rn. Roy. A nthrop l nst., vol. lxviii , (1938) , pp. 17- 98. WOOLDRIDGE, S. W. 193 8. The Glaciation of the London Basin a nd the Evolution of the Lower Thames Draina ge Sy stem . Quart . Journ. Geol, Soc., vol. xciv ., pp. 627- 664.