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The status of the Hill House ‘Formation’ at Happisburgh, Norfolk, England
Quaternary International 271 (2012) 29e30
Contents lists available at SciVerse ScienceDirect
Quaternary International journal homepage: www.elsevier.com/locate/quaint
The status of the Hill House ‘Formation’ at Happisburgh, Norfolk, England Philip Gibbard Cambridge Quaternary, Department of Geography, University of Cambridge, Cambridge CB2 3EN, England, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 22 September 2011
Sediments at a site at Happisburgh, Norfolk, from which an important assemblage of flint artefacts had been excavated, were recently described. This locality, termed Happisburgh 3 (NGR TG380313; 52 49_3600 N, 131_5800 E), occurs on the NE coast of Norfolk. These sediments consist of a complex of freshwater, estuarine and inter-tidal deposits, which were deposited during the Early and early Middle Pleistocene. These deposits were defined as an independent lithostratigraphical unit, the Hill House Formation. However, as the deposits already formed part of the Cromer Forest-bed Formation, they cannot themselves have the same status. It is therefore proposed that the unit be referred to as the Hill House Member of the Cromer Forest-bed Formation. Ó 2011 Elsevier Ltd and INQUA. All rights reserved.
1. Discussion The subdivision of geological sequences on the basis of the physical properties of the sediments is lithostratigraphy. If this is undertaken in a meaningful, practical manner, as in all stratigraphical classification, this division is hierarchical. The principal intention of this approach is that the division reflects reality as far as possible, whilst also facilitating efficient communication. Implicit in this division is that the hierarchical level at which any individual unit is defined has no bearing on its perceived importance: rather it should recognise the unit’s scale and extent within the regional sequence. In a recent article, Parfitt et al. (2010) described a site at Happisburgh, Norfolk, England from which an important assemblage of flint artefacts had been excavated. This locality, termed Happisburgh 3 (NGR TG380313; 52 490 3600 N, 13105800 E), occurs on the north-eastern coast of Norfolk. It consists of a series of fluvial gravels and laminated estuarine sands and silts that fill a series of stacked, overlapping channels exposed on the foreshore. These sediments consist of a complex of freshwater, estuarine and intertidal sediments, defined as the Cromer Forest-bed Formation (CFBF), that were deposited in this area during the Early and early Middle Pleistocene (West and Wilson, 1966; Funnell and West, 1977; West, 1980). These CFBF sediments underlie the Happisburgh Diamicton, the lowest member of the Anglian-age North Sea Drift (‘Happisburgh’) Formation (equated to Marine Isotope Stage [MIS] 12: Gibbard and Clark, 2011), and overlie bedrock Chalk, or Early Pleistocene Crag Group sediments.
E-mail address: [email protected]. 1040-6182/$ e see front matter Ó 2011 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2011.09.014
The sediments from which the artefacts were obtained at the Happisburgh Site 3, include a complex of eight beds (AeH) (Parfitt et al., 2010, Supplementary information 1, table 3), which is interpreted as representing evolving channel forms and their infilling. They are considered equivalent to West’s (1980) beds i and j in his borehole HCS9, together indicating a channel complex c. 700 m in width. On the basis of their “clearly defined geometry and sedimentology” and that they “may be traced for a considerable distance along the coast” (Parfitt et al., 2010, Supplementary information 1, table 2), it is proposed that the unit should be defined as an independent lithostratigraphical unit, the Hill House Formation (Parfitt et al., 2010, Supplementary information 1: table 2). The geological evidence, in particular the gravel clast lithology, implies that the deposits represent the fluvio-estuarine zone of an early course of the River Thames (Parfitt et al., 2010, Supplementary information 1). Whilst the definition of a new lithostratigraphical unit appears justified on the basis of the detailed information assembled by Parfitt et al. (2010), and the recognition that the sediments comprise a discrete sedimentary complex, partially independent of other accumulations in the area, it is questionable whether this unit should be assigned formation-status. The only justification offered for this status is that the deposits are ‘mappable’, a criterion that is considered a basic requirement of lithostratigraphical formations (e.g. Salvador, 1994). Whilst this is not questioned, it is certainly reasonable to state that all sediment units should be mappable at an appropriate scale. As, in this case, the sediments can only be identified over a lateral distance of c. 700 m, and at present there is no knowledge of their extension either inland or offshore, their mappability is an insufficient criterion by itself to justify the status assigned to the unit. Moreover, it could be considered that this lack
30
P. Gibbard / Quaternary International 271 (2012) 29e30
of evidence of the unit’s continuity might render it better suited to an informal, rather than a formal, definition until more evidence becomes available. However, there is a second, greater obstacle to the unit being formalised at formation-status: it was already included within a formation-status unit before the recent study began. Following earlier workers, the sediments investigated were included within the CFBF, defined by West (1980), as Parfitt et al. (2010) state. Since formations cannot themselves include divisions of the same status, the Hill House unit cannot be assigned formation-status, i.e. a status equivalent to the whole of the CFBF or similar large-scale divisions of the Pleistocene sequence. Unless it can be shown to be distinct from the CFBF on the basis of its lithostratigraphy alone, which it cannot at present, there is no reason to separate it. Therefore, since this separation from the CFBF cannot be justified, what status should the unit have? Considering the scale of the Hill House unit and its comparison with similar divisions both within the CFBF (e.g. the West Runton Freshwater Bed: West and Wilson, 1966; Funnell and West, 1977; West, 1980; Gibbard and Zalasiewicz, 1988; Gibbard et al., 1991) and other formations in the region (e.g. McMillan et al., 2004), such as those of the Thames deposits of which the unit apparently forms a part, the most appropriate status would be that of a Member (assuming that it requires formal definition). Such a change of status places the unit in its correct hierarchical position within the divisions of the East Anglian Pleistocene and in no way diminishes its importance in the regional succession. It is therefore proposed that hence-forward the unit be referred to as the Hill House Member of the Cromer Forest-bed Formation. 2. Postscript The lesson from this exercise is clear. The definition of lithostratigraphical units should ideally be managed by a national organisation: in Britain this could be the British Geological Survey (BGS). Unfortunately, unlike in the Netherlands and elsewhere, until very recently in Britain there has been limited co-ordination or consistency in the division of the Quaternary sedimentary record, despite attempts by the Geological Society’s Stratigraphy Commission (e.g. Bowen, 1999). In the absence of a national officiating body, care should be taken to ensure compatibility in scale and consistency of hierarchical position of any unit defined, as well as consideration of the utility of formally defining sediment units. The definition of formation- or larger scale units on the basis of limited exposure and extent does not clarify communication, nor is
it necessary that the importance of a unit should be reflected by it being defined at a higher hierarchical level in order to confirm its perceived status. When this is done, the proliferation of terms is of little practical value. Practicality should be the guiding principle in lithostratigraphical subdivision, as in all classificatory schemes (Salvador, 1994; Räsänen et al., 2009; Hughes, 2010). A balance should be sought to ensure that, when divisions are proposed, they are defined at the appropriate scale and are consistently applied to enhance and clarify communication, while respecting historical precedence. Acknowledgements I thank Dr Wim Westerhoff for critically reading the text and for his helpful suggestions, Dr Katharine MacDonald for editorial assistance and two referees for their helpful suggestions. References Bowen, D.Q., 1999. A revised correlation of the Quaternary deposits in the British Isles. Geological Society Special Report 23, 79e90. Funnell, B.M., West, R.G., 1977. Preglacial Pleistocene deposits of East Anglia. In: Shotton, F.W. (Ed.), British Quaternary Studies. Clarendon Press, Oxford, pp. 247e265. Gibbard, P.L., Clark, C.D., 2011. Pleistocene glaciation limits in Great Britain. In: Ehlers, J., Gibbard, P.L., Hughes, P.D. (Eds.), Quaternary Glaciation Extent and Chronology: A Closer Look. Elsevier, Amsterdam, pp. 75e93. Gibbard, P.L., West, R.G., Zagwijn, W.H., Balson, P.S., Burger, A.W., Funnell, B.M., Jeffery, D.H., De Jong, J., Van Kolfschoten, T., Lister, A.M., Meijer, T., Norton, P.E.P., Preece, R.C., Rose, J., Stuart, A.J., Whiteman, C.A., Zalasiewicz, J.A., 1991. Early and early Middle Pleistocene correlations in the southern North Sea Basin. Quaternary Science Reviews 10, 23e52. Gibbard, P.L., Zalasiewicz, J.A., 1988. The Pliocene to early Middle Pleistocene of East Anglia: an overview. In: Zalasiewicz, J.A., Gibbard, P.L. (Eds.), PlioceneeMiddle Pleistocene of East Anglia. Quaternary Research Association, Cambridge. Hughes, P.D., 2010. Geomorphology and Quaternary stratigraphy: the roles of morpho-, litho-, and allostratigraphy. Geomorphology 123, 189e199. McMillan, A.A., Hamblin, R.J.O., Merritt, J.W., 2004. An overview of the lithostratigraphical framework for Quaternary and Neogene deposits of Great Britain (onshore). British Geological Survey Research Report. RR/04/04. Parfitt, S.A., Ashton, N., Lewis, S.G., Abel, R.L., Coope, G.R., Field, M.H., Gale, R., Hoare, P.G., Larkin, N.R., Lewis, M.D., Karloukovski, V., Maher, B.A., Peglar, S.M., Preece, R.C., Whittaker, J.E., Stringer, C.B., 2010. Early Pleistocene human occupation at the edge of the boreal zone in northwest Europe. Nature 466, 229e233. Räsänen, M.E., Auir, J.M., Huitti, J.V., Klap, A.K., Virtasalo, J.J., 2009. A shift from lithostratigraphic to allostratigraphic classification of Quaternary glacial deposits. GSA Today 19, 4e11. Salvador, A., 1994. International Stratigraphic Guide. A Guide to Stratigraphic Classification, Terminology and Procedures, second ed. Geological Society of America, Boulder, CO. 220. West, R.G., 1980. The Pre-Glacial Pleistocene of the Norfolk and Suffolk Coasts. Cambridge University Press, Cambridge. 203. West, R.G., Wilson, D.G., 1966. Cromer forest bed series. Nature 209, 497e498.
Contents lists available at SciVerse ScienceDirect
Quaternary International journal homepage: www.elsevier.com/locate/quaint
The status of the Hill House ‘Formation’ at Happisburgh, Norfolk, England Philip Gibbard Cambridge Quaternary, Department of Geography, University of Cambridge, Cambridge CB2 3EN, England, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 22 September 2011
Sediments at a site at Happisburgh, Norfolk, from which an important assemblage of flint artefacts had been excavated, were recently described. This locality, termed Happisburgh 3 (NGR TG380313; 52 49_3600 N, 131_5800 E), occurs on the NE coast of Norfolk. These sediments consist of a complex of freshwater, estuarine and inter-tidal deposits, which were deposited during the Early and early Middle Pleistocene. These deposits were defined as an independent lithostratigraphical unit, the Hill House Formation. However, as the deposits already formed part of the Cromer Forest-bed Formation, they cannot themselves have the same status. It is therefore proposed that the unit be referred to as the Hill House Member of the Cromer Forest-bed Formation. Ó 2011 Elsevier Ltd and INQUA. All rights reserved.
1. Discussion The subdivision of geological sequences on the basis of the physical properties of the sediments is lithostratigraphy. If this is undertaken in a meaningful, practical manner, as in all stratigraphical classification, this division is hierarchical. The principal intention of this approach is that the division reflects reality as far as possible, whilst also facilitating efficient communication. Implicit in this division is that the hierarchical level at which any individual unit is defined has no bearing on its perceived importance: rather it should recognise the unit’s scale and extent within the regional sequence. In a recent article, Parfitt et al. (2010) described a site at Happisburgh, Norfolk, England from which an important assemblage of flint artefacts had been excavated. This locality, termed Happisburgh 3 (NGR TG380313; 52 490 3600 N, 13105800 E), occurs on the north-eastern coast of Norfolk. It consists of a series of fluvial gravels and laminated estuarine sands and silts that fill a series of stacked, overlapping channels exposed on the foreshore. These sediments consist of a complex of freshwater, estuarine and intertidal sediments, defined as the Cromer Forest-bed Formation (CFBF), that were deposited in this area during the Early and early Middle Pleistocene (West and Wilson, 1966; Funnell and West, 1977; West, 1980). These CFBF sediments underlie the Happisburgh Diamicton, the lowest member of the Anglian-age North Sea Drift (‘Happisburgh’) Formation (equated to Marine Isotope Stage [MIS] 12: Gibbard and Clark, 2011), and overlie bedrock Chalk, or Early Pleistocene Crag Group sediments.
E-mail address: [email protected]. 1040-6182/$ e see front matter Ó 2011 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2011.09.014
The sediments from which the artefacts were obtained at the Happisburgh Site 3, include a complex of eight beds (AeH) (Parfitt et al., 2010, Supplementary information 1, table 3), which is interpreted as representing evolving channel forms and their infilling. They are considered equivalent to West’s (1980) beds i and j in his borehole HCS9, together indicating a channel complex c. 700 m in width. On the basis of their “clearly defined geometry and sedimentology” and that they “may be traced for a considerable distance along the coast” (Parfitt et al., 2010, Supplementary information 1, table 2), it is proposed that the unit should be defined as an independent lithostratigraphical unit, the Hill House Formation (Parfitt et al., 2010, Supplementary information 1: table 2). The geological evidence, in particular the gravel clast lithology, implies that the deposits represent the fluvio-estuarine zone of an early course of the River Thames (Parfitt et al., 2010, Supplementary information 1). Whilst the definition of a new lithostratigraphical unit appears justified on the basis of the detailed information assembled by Parfitt et al. (2010), and the recognition that the sediments comprise a discrete sedimentary complex, partially independent of other accumulations in the area, it is questionable whether this unit should be assigned formation-status. The only justification offered for this status is that the deposits are ‘mappable’, a criterion that is considered a basic requirement of lithostratigraphical formations (e.g. Salvador, 1994). Whilst this is not questioned, it is certainly reasonable to state that all sediment units should be mappable at an appropriate scale. As, in this case, the sediments can only be identified over a lateral distance of c. 700 m, and at present there is no knowledge of their extension either inland or offshore, their mappability is an insufficient criterion by itself to justify the status assigned to the unit. Moreover, it could be considered that this lack
30
P. Gibbard / Quaternary International 271 (2012) 29e30
of evidence of the unit’s continuity might render it better suited to an informal, rather than a formal, definition until more evidence becomes available. However, there is a second, greater obstacle to the unit being formalised at formation-status: it was already included within a formation-status unit before the recent study began. Following earlier workers, the sediments investigated were included within the CFBF, defined by West (1980), as Parfitt et al. (2010) state. Since formations cannot themselves include divisions of the same status, the Hill House unit cannot be assigned formation-status, i.e. a status equivalent to the whole of the CFBF or similar large-scale divisions of the Pleistocene sequence. Unless it can be shown to be distinct from the CFBF on the basis of its lithostratigraphy alone, which it cannot at present, there is no reason to separate it. Therefore, since this separation from the CFBF cannot be justified, what status should the unit have? Considering the scale of the Hill House unit and its comparison with similar divisions both within the CFBF (e.g. the West Runton Freshwater Bed: West and Wilson, 1966; Funnell and West, 1977; West, 1980; Gibbard and Zalasiewicz, 1988; Gibbard et al., 1991) and other formations in the region (e.g. McMillan et al., 2004), such as those of the Thames deposits of which the unit apparently forms a part, the most appropriate status would be that of a Member (assuming that it requires formal definition). Such a change of status places the unit in its correct hierarchical position within the divisions of the East Anglian Pleistocene and in no way diminishes its importance in the regional succession. It is therefore proposed that hence-forward the unit be referred to as the Hill House Member of the Cromer Forest-bed Formation. 2. Postscript The lesson from this exercise is clear. The definition of lithostratigraphical units should ideally be managed by a national organisation: in Britain this could be the British Geological Survey (BGS). Unfortunately, unlike in the Netherlands and elsewhere, until very recently in Britain there has been limited co-ordination or consistency in the division of the Quaternary sedimentary record, despite attempts by the Geological Society’s Stratigraphy Commission (e.g. Bowen, 1999). In the absence of a national officiating body, care should be taken to ensure compatibility in scale and consistency of hierarchical position of any unit defined, as well as consideration of the utility of formally defining sediment units. The definition of formation- or larger scale units on the basis of limited exposure and extent does not clarify communication, nor is
it necessary that the importance of a unit should be reflected by it being defined at a higher hierarchical level in order to confirm its perceived status. When this is done, the proliferation of terms is of little practical value. Practicality should be the guiding principle in lithostratigraphical subdivision, as in all classificatory schemes (Salvador, 1994; Räsänen et al., 2009; Hughes, 2010). A balance should be sought to ensure that, when divisions are proposed, they are defined at the appropriate scale and are consistently applied to enhance and clarify communication, while respecting historical precedence. Acknowledgements I thank Dr Wim Westerhoff for critically reading the text and for his helpful suggestions, Dr Katharine MacDonald for editorial assistance and two referees for their helpful suggestions. References Bowen, D.Q., 1999. A revised correlation of the Quaternary deposits in the British Isles. Geological Society Special Report 23, 79e90. Funnell, B.M., West, R.G., 1977. Preglacial Pleistocene deposits of East Anglia. In: Shotton, F.W. (Ed.), British Quaternary Studies. Clarendon Press, Oxford, pp. 247e265. Gibbard, P.L., Clark, C.D., 2011. Pleistocene glaciation limits in Great Britain. In: Ehlers, J., Gibbard, P.L., Hughes, P.D. (Eds.), Quaternary Glaciation Extent and Chronology: A Closer Look. Elsevier, Amsterdam, pp. 75e93. Gibbard, P.L., West, R.G., Zagwijn, W.H., Balson, P.S., Burger, A.W., Funnell, B.M., Jeffery, D.H., De Jong, J., Van Kolfschoten, T., Lister, A.M., Meijer, T., Norton, P.E.P., Preece, R.C., Rose, J., Stuart, A.J., Whiteman, C.A., Zalasiewicz, J.A., 1991. Early and early Middle Pleistocene correlations in the southern North Sea Basin. Quaternary Science Reviews 10, 23e52. Gibbard, P.L., Zalasiewicz, J.A., 1988. The Pliocene to early Middle Pleistocene of East Anglia: an overview. In: Zalasiewicz, J.A., Gibbard, P.L. (Eds.), PlioceneeMiddle Pleistocene of East Anglia. Quaternary Research Association, Cambridge. Hughes, P.D., 2010. Geomorphology and Quaternary stratigraphy: the roles of morpho-, litho-, and allostratigraphy. Geomorphology 123, 189e199. McMillan, A.A., Hamblin, R.J.O., Merritt, J.W., 2004. An overview of the lithostratigraphical framework for Quaternary and Neogene deposits of Great Britain (onshore). British Geological Survey Research Report. RR/04/04. Parfitt, S.A., Ashton, N., Lewis, S.G., Abel, R.L., Coope, G.R., Field, M.H., Gale, R., Hoare, P.G., Larkin, N.R., Lewis, M.D., Karloukovski, V., Maher, B.A., Peglar, S.M., Preece, R.C., Whittaker, J.E., Stringer, C.B., 2010. Early Pleistocene human occupation at the edge of the boreal zone in northwest Europe. Nature 466, 229e233. Räsänen, M.E., Auir, J.M., Huitti, J.V., Klap, A.K., Virtasalo, J.J., 2009. A shift from lithostratigraphic to allostratigraphic classification of Quaternary glacial deposits. GSA Today 19, 4e11. Salvador, A., 1994. International Stratigraphic Guide. A Guide to Stratigraphic Classification, Terminology and Procedures, second ed. Geological Society of America, Boulder, CO. 220. West, R.G., 1980. The Pre-Glacial Pleistocene of the Norfolk and Suffolk Coasts. Cambridge University Press, Cambridge. 203. West, R.G., Wilson, D.G., 1966. Cromer forest bed series. Nature 209, 497e498.