The Shotton Project
University of Birmingham. Includes:
Ice Age in the Midlands
from the Shotton project
Geology( including Quaternary) of Hertfordshire. By Dr. John Catt
The Ice Ages in the early and middle Pleistocene.
Conference abstract
Pleistocene of the Thames. Chapter 1 of GCR Quaternary of the Thames. (PDF file)

Ice Age Britain Home

In 1973 Mitchell et. al. had devised a stratigraphy and correlation of the British Pleistocene that was contested from the date of publication.  The stratigraphy was based upon the interpretation of a wide range of evidence from around the British Isles. In 1986 a different correlation was devised by Bowen et. al. The publication produced argued for more local, regional stratigraphies that could be partly correlated. The most contentious issues were focussed upon the status of the Wolstonian glaciation. The Wolstonian type site is in the midlands.  Most recent research suggests that there has been a misinterpretation of the type site.  Yet there is still strong evidence for a Wolstonian type glaciation, and new sites in the midlands are greatly expanding our knowledge of the middle Pleistocene in Britain.  So what of the Wolstonian?

In order to fully understand the nature of the problems surrounding the interpretation of the middle Pleistocene in the UK we shall need to appreciate the nature of the evidence, and how it has been interpreted in the past. Problems arise because of inappropriate methodologies that have been employed in attempting to understand the terrestrial record. Therefore a review of the field evidence and of the nature of 'glacial' and interglacial' episodes is required. The classical 'newer' and 'older' drift sequences are easily identified in East Anglia. Difficulties arise in East Anglia because the area was affected by ice sheets from two different sources (one Scandinavian and the other British), but the exact number of times that the land was inundated by ice is far from clear. Furthermore, ice from British sources seems to have deposited diamicts whose clast lithology is spatially variable. Whether the diamicts of differing provenance represent different glaciations from different time periods, or changes in the dynamics of an ice sheet within a single glaciation, or simply a natural lateral variation in basal ice conditions is unclear.

Please note: the literature abounds with a bewildering plethora of names for glaciations, glacial deposits and type sites that can be very confusing. I can only present a rather simplified account if I wish to avoid creating confusion. When you consult the literature you will encounter these names - seek advice if you are confused.

In order to fully appreciate current interpretations and controversy regarding the Quaternary of central and eastern England, we will therefore begin with a look at the 'classical' interpretations, then the revisions, and finally the current state of affairs with regard to the field evidence. The map below shows the location of some important sites.

The Classical Scenario

The Quaternary of Eastern England

Glacial Evidence

East Anglia would appear to have the most complete record of Quaternary sediments in the UK. The Anglian episode is so named because the greater part of the evidence for events around this time period (450,000 years b.p.) comes from East Anglia. The best sequences are exposed in cliff sections of the Norfolk and Suffolk coast. As one moves south along the coastline one encounters progressively older diamict sequences that reflect the complexity of the Anglian cold stage. The Holderness coast of east Yorkshire has the better exposures of Devensian glacial sediments. Some Devensian deposits can also be found in East Anglia, and thus the newer drift and older drift provinces of East Anglia were established in the first half of the 20th century.

Although a number of different names have been applied to glacial sediments of the region, by the 1960s a third glaciation was recognised in East Anglia, the 'Gipping' glaciation (named after sediments exposed in the Gipping Valley, Suffolk). This glaciation was differentiated from the older Lowestoft glaciation, whose 'Chalky till' is the most widespread. The Gipping till in turn is older than the Hunstanton till, the latter is equated with the newer drift and is Devensian in age.

Interglacial evidence

The evidence for warm ('interglacial') episodes in East Anglia is quite widespread. Pollen analysis of organic sediments has revealed two apparently distinct warm periods. On the one hand are deposits that yield a flora that appears very similar to that found at the type site for the Ipswichian interglacial, at Bobbitshole. On the other, there are deposits that resemble those found at the type-site for the Hoxnian interglacial, at Hoxne.

Arboreal pollen profiles for 2 Pleistocene interglacials.

(Modified after a number of authors, principally West, 1977, and Bowen 1978).

In fact, neither Bobbitshole or Hoxne yielded pollen profiles for an entire interglacial cycle. Ipswichian sites seem to fall into one of two categories: either organic sequences contain profiles for the early phases of the interglacial, or later phases. This may be significant. An entire 'interglacial' sequence was found at Marks Tey, Essex, that was ascribed to the Hoxnian interglacial.

Putting the evidence together

The presence of the two distinct organic deposits has enabled stratigraphic relationships between diverse inorganic deposits to be determined. Indeed at the time when the majority of these deposits were discovered (mid 1950s through to the early 1970s), interglacial pollen profiles were seen as the main means of dating inorganic glacial deposits. The relationship of a till to interglacial deposits (whether it lay stratigraphically above or below Hoxnian or Ipswichian interglacial deposits) enabled dating of glacial deposits within the British Sequence.

The interglacial deposits of the Hoxnian and Ipswichian were, of course, quite well stratigraphically constrained. Their relative ages to each other were determined by their stratigraphical relationship to glacial deposits. Interglacial sediments could be dated (relatively) according to their stratigraphical location within the sequence of glacial and cold climate deposits. (The more keenly aware amongst you may begin to see something of a flaw in thinking here...).

Although abundant, the evidence from East Anglia is equivocal. The stratigraphical relationships between the deposits of different ages was suggested as below (both East Anglian and UK stage names are given).

Unfortunately, no-one could point to any Ipswichian deposit in East Anglia that lay upon glacial deposits that were proven (i.e. by independent dating) to post-date the Anglian. This means that it is always entirely possible that Ipswichian deposits could have been deposited upon Anglian deposits, therefore implying an unconformity within which Hoxnian and Wolstonian deposits were missing (not an unreasonable proposition). If you wished to argue an Anglian age for a till beneath Ipswichian sediments, you had to invoke an unconformity; well, either that, or, it is possible that the Hoxnian interglacial is in fact the same as thing as the Ipswichian, and Gipping glaciation did not exist (except as part of the Anglian). Now this sort of nonsense we could do without, quite frankly; it is terribly confusing. The easiest thing to do is to accept that if an Ipswichian deposit is found on top of a cold climate deposit, that the cold climate sediments are of Gipping (Wolstonian ) age. After all, the definition (or at least part of it) of the Gipping is its pre-Ipswichian age.

Similarly, there is no location in East Anglia where Hoxnian deposits are found underneath glacial deposits that can be positively demonstrated to pre-date the Devensian glaciation. Hoxnian sediments are most commonly found in hollows eroded into Anglian deposits, and may be covered by a variety of sediments, including Holocene alluvium. It was always entirely possible that in locations where Hoxnian-type deposits were overlain by glacially derived sediments, that glacial sediments were Devensian in origin. Thus, there is an unconformity within which the Wolstonian and Ipswichian periods are lost (not unreasonable) or we could invoke the entirely implausible notion that the Hoxnian and Ipswichian were, broadly speaking, the same interglacial, and that the Gipping does not exist. Either that or stop mucking about and call the glacially derived sediments on top of Hoxnian deposits 'Gipping' (Wolstonian). After all, part of the definition of the Gipping is its post-Hoxnian age.

To be concise, there is nowhere in East Anglia where a sequence of deposits, as suggested in the table above, exists. There is conclusive evidence of a pre-Hoxnian glaciation, and a post-Ipswichian glaciation. Glaciation prior to the Ipswichian is undoubted, as is glaciation following the Hoxnian, but a specifically post-Hoxnian, pre-Ipswichian glaciation is not represented by a ubiquitous glacial diamict. There is a diamict that is confined to isolated interfluves and valley bottoms. The diamict is often assigned to the Gipping, and is also sometimes known as a 'chalky boulder clay'. The Devensian (Hunstanton) drift is not a chalky boulder clay. The trouble is, the Lowestoft till is a chalky boulder clay. The Lowestoft is Anglian, the Gipping is younger, because it post-dates the Hoxnian. (Study this last sentence very carefully).

What is needed is a sequence of Hoxnian and Ipswichian deposits, in situ, that are separated by glacial deposits. If we cannot find them in East Anglia, we need to look elsewhere beyond the newer drift limit, where there are extensive older drift deposits. Like the Midlands, for example.

The Quaternary of the English Midlands.

There are three key sites to examine here, Nechells, Quinton and Wolston (the latter being the type site for the Wolstonian). At both Quinton and Nechells, interglacial sediments are found that are both underlain and overlain by glacigenic sediment. At both sites the organic sediments have yielded pollen that suggest that a fully temperate flora developed, and the flora is very comparable to East Anglian Hoxnian flora. Therefore the interglacial stage represented at the sites has been ascribed to the Hoxnian. The glacial stage represented by the lower glacial sediment is, by definition, Anglian in age. The glacial deposits above the organic sequences represent a post- Anglian glaciation. A Devensian origin is discounted since the 'Wolverhampton line' -the widely accepted newer drift or Devensian limit- is well to the north. The only glacial left to which the upper glacigenic sediments can be correlated is the East Anglian 'Gipping' glaciation. Of course it would be better if the upper tills at both Nechells and Quinton could be correlated to a more local post Hoxnian glaciation. Fortunately there is a wonderful glacigenic sequence at Wolston, Warwicks.

The type site for the Wolstonian is a remarkable sequence of glacially derived gravels, lake clays and diamicts. The site (a quarry) has been slightly revised in terms of interpretation over the years since it was first described. Therefore the sequence of deposits presented below is a simplification that contains the essence of an interpretation of the classical sequence, but not the detail. You will find variations in the literature.

Table 1. The classical Wolston sequence.

The sequence was interpreted as demonstrating a significant history of environmental change throughout the glacial period that was termed 'the Wolstonian'. The Wolstonian cold period was placed between the Hoxnian and Ipswichian interglacial periods for a number of reasons. As the site and associated widespread deposits were beyond the limit of the Devensian glaciation, they clearly pre-dated the Devensian, and there is strong evidence to show that the sequence predated the Ipswichian interglacial. Furthermore Shotton, who first described the till and lake sediments, correlated the entire glacigenic sequence with the glacigenic deposits found above the Hoxnian organics at Quinton and Nechells. The final justification for the Wolstonian interpretation came from the correlation of the Oadby till with the Gipping till. This was not unreasonable, after all both the East Anglian (Gipping) and Midlands (Oadby) till were 'Chalky' tills.

Summary of the Classical Interpretations

In East Anglia the 'Gipping' (Wolstonian) glaciation is hard to pin down. In some places a chalky boulder clay can be found beneath Hoxnian sediments. This is the Anglian till. In other places a chalky boulder clay can be found beneath Ipswichian sediments. This is the Gipping till. Unfortunately there is no site where the Gipping till is seen to overly Hoxnian sediments and is capped by Ipswichian sediments. In the midlands Hoxnian interglacial deposits, sandwiched by glacial tills is found at Quinton. The upper till at Quinton is beyond the limits of the Devensian, and is therefore correlated with the Gipping till of East Anglia, but the glacial period post-dating the Hoxnian is better represented by the diamict sequence at Wolston.

Revising the Interpretation

Problems with the sequence

Throughout much of the foregoing I have hinted at some problems of interpretation of the Pleistocene sediments of East Anglia. And problems there are.

At this point I must begin to mention 'the literature'. Thus far I have avoided references to the literature, I do not wish to see you scurrying after every last scrap of discernibly relevant material. From this point forward I will mention certain key publications, although I do not expect you to read everything. Be selective. Take Mitchell et. al. (1973); or rather, don't take Mitchell &c; it will only serve to confuse you. But I will refer to it.

Problems with the Glacial sequence

The publication of the Correlation of Quaternary Deposits in the British Isles was accompanied by controversy the moment it was published in 1973. In the same year (and is even mentioned in the publication), Bristow and Cox published new evidence that suggested that the Lowestoft Till and the Gipping Till were one and the same thing. This caused a bit of a stir. A few more papers followed throughout the 1970s that looked at the 'chalky tills' of East Anglia and the Midlands, most of which concluded that the chalky tills could not be differentiated. The age of the tills was still a matter of debate, although to some an Anglian age could not be disputed. A very robust account of the issues is presented by Cox (1981).

With the Gipping glaciation discounted, there was an issue with the Wolstonian. The type site was correlated with the Gipping (or at least the Oadby till was), yet the type site was not directly correlated with any other sequence of glacial or interglacial sediments. In terms of geology, this is a very bizarre situation. Without accompanying interglacial deposits, the type site can only be correlated on the basis of till lithology. Equating the Oadby till with the Gipping till was a problem for Shotton, who first described the Wolston site in 1953 (Shotton, 1989). The argument over the Gipping till was largely over and settled by the early 1980s, in favour of those who saw a single Anglian chalky till in East Anglia. Logically, then, the Uppermost Wolston till must be Anglian in age, and therefore, so is the whole sequence.

The mention of Perrin et. al.(1973, 1979) within the foregoing is a reference to a further attack upon the type Wolstonian sequence: the sequence was not only attacked from above (Oadby till) it was undermined from below (Baginton gravels). Rose (1987, 1989) correlated the Baginton-Lillington gravels with gravels of Anglian age (Ingham gravels). Thus by the late 1980s the Wolstonian type site, and the East Anglian tills with which it was initially correlated, was seriously challenged. But what did this mean for the interglacials?

Problems with the interglacial sequence.

As early as the 1970s problems with the interglacial evidence were recognised. The classical interglacial floristic sequences could clearly be diachronous: in a climatically variable region such as the UK, it is not reasonable to expect that a uniform development of tree colonisation occurs during warm periods. Furthermore, it is possible that more than one interglacial experiences very similar patterns of vegetation change. Just because two pollen diagrams appear to be similar, it does not mean that they are of the same age. When two interglacial deposits present similar pollen profiles, but contain suites of very different mammalian fossils, questions need to be asked. And questions certainly were asked about about certain Ipswichian sites in the Thames basin during the 1970s. I do not wish to stray too far from my chosen regions, but it is important to recognise that evidence from across the British Isles is pertinent.

Certain important sites within the Thames basin, which have been classified as 'Ipswichian' due to their flora, have different mammalian fossil assemblages associated with them. The deposits are also topographically difficult to correlate. Strong arguments have been put forward that more than one 'Ipswichian' episode followed the classical Wolstonian stage (i.e. post-dated the chalky till event). In the Irish republic an even more strange occurrence is noted. Many interglacial sites have been discovered that strongly resemble the Hoxnian type flora (Hippophae and 'Type X' pollen being the most distinctive elements). Yet there are few, if any, sites that closely resemble East Anglian Ipswichian sites. So what do we conclude? One could argue that only the Anglian, Hoxnian (known as the Gortian in Ireland) and Devensian are represented by Irish mid to late Pleistocene sedimentation. Alternatively, one can argue that the present day flora of the west of Ireland is very different from that of East Anglia, and that we are therefore not surprised that a) Irish Ipswichian floras are very different from East Anglian Ipswichian floras; and b) we are not surprised that succeeding Irish interglacials produce very similar floral stages, given an extreme Atlantic location.

In England there is good evidence to support the idea that Classical Hoxnian and Ipswichian interglacial episodes exist. There is also good evidence that more than one Hoxnian, and more than Ipswichian episode exists as well. Ooops.

Problems with oxygen, problems with stratigraphy.

Early in the 1970s, evidence was published concerning ocean floor sediments that had been analysed for their oxygen isotope record contained within calcareous sediment. The evidence was startling: at least 24 cold periods characterised the Pleistocene, and the cold periods were separated by much shorter lived warm periods. The evidence confirmed the solar forcing theories of Milankovitch (see last years Landscape Development lectures); and blew the long accepted Penck-Brückner type schemes completely out of the water.

All along the problem had been the Penck & Brückner type scheme. The Alpine model of Quaternary time had also been recognised on the northern European plain, and the two schemes were directly correlated. This is the source of the problem in interpreting the Quaternary of the UK. Prior to WW II, as said earlier in the course, the Quaternary of the UK was not fashionable, and little (relatively) effort was put into interpreting the sequence of Pleistocene deposits. A few interested geologists had continued with Victorian traditions, and had identified and differentiated glacial deposits according to lithology, and repeatedly uncovered the 'Tripartite sequence' of newer and older drift. Following W.W.II Quaternary Science was reinvigorated. To many people it was obvious that if a four-fold model of glaciation could be recognised in Holland and northern Germany, then the pattern must be repeated in Britain - and so the evidence needed to be looked at afresh. In much of the foregoing I have deliberately given a slightly false impression, that basic errors were made in interpreting the UK sequence because of woolly thinking. This is not really fair. If a four fold sequence could be identified in the Alps, the German plain and the United States, why not in Britain, which at least had its own ice sheet, goddammit?

With the benefit of hindsight, we can argue that both the new/old drift school, and those that believed that there must have been more than two glaciations of Britain, were right. The new/old drift school were right because they only reported field stratigraphy. I may be wrong, but I do not believe that there is anywhere in the UK where it is possible to demonstrate a sequence of three glacial diamictons separated by non-glacial sediment. On the other hand, if more than two glaciations are recognised elsewhere in the world, surely there is something wrong with our interpretations of the British sequence. With hindsight, we can argue that both schools of thought were equally wrong.

This is the nature of the problem. Once you have a model of temporal events, it is easy to shoehorn the evidence to fit the model. The main lesson to learn is that despite our new model (now we can recognise at least 36 cold stages in the Quaternary from oxygen isotope records), we must be wary of shoehorning evidence into this new, very much bigger, shoe.

Correlation with the Oxygen Isotope Curve.

The oxygen isotope curve needed to be reckoned with, but it was difficult, even in the 1980s, to produce dates from the field evidence that were certain. Correlation of the more recent stages was easy, but as we go back in time problems arise. By 1986, the following scheme was broadly accepted. (Bowen et. al., 1986, in Sibrava et. al.)

Table 2. The Oxygen Isotope sequence and UK terrestrial stages

Here again I am cutting one or two corners, but never mind. Note that I assign an oxygen isotope stage to the Wolstonian. In the publication referred to above, Shotton was allowed space to defend his Wolstonian glaciation. Many other people by 1986 disagreed with him, but, crucially, the Oxygen isotope curve did suggest a cold enough period during stage 6 to allow for a glacial episode of the Wolstonian type. New Shoes, New Shoehorn?

The problem posed by the evidence from ocean floor sediment studies is blindingly obvious. Look at the table again, remembering that OI stages still basically represent cold 'glacial' stages (even numbers) and warm, temperate stages (odd numbers). Where are OI stages 11 & 10, 8 & 7?

The answer is probably obvious by now. The worries over the Ipswichian evidence actually suggests that some 'Ipswichian' (sensu stricto) sites are not stage 5e in age, but are possibly stage 7. Similarly, certain 'Hoxnian' sites may well belong to stage 11 and 9. The dating of certain cold stages in relation to these interglacials is therefore possibly insecure. It is now believed that the Hoxnian type-site sediments should be ascribed to OI stage 11 (Lewis S.G et al., 2000).

Thus in the late 1980s, the status of the 'Wolstonian' was equivocal. On the one hand, both the stratotype (the Wolston sequence) had been correlated with the Anglian glaciation; as had its most important East Anglian counterpart (the Gipping till). On the other hand, tentative evidence for a pre-Ipswichian but post Hoxnian (or post Anglian ) glaciation was recognised in a number of different locations, including the Gower in Wales (Bowen, 1986), in north east England (Rose 1986), in Norfolk (in the Nar valley, Gibbard et. al., 1992) and more recently in the south Midlands (Lewis & Maddy, 1997). Evidence for a Wolstonian type glaciation in Lincolnshire was also recognised by some (Jones and Keen, 1993) and the problem of OI stage 6 still remained.

To some the answer was obvious. Even though the type site was flawed, a cold period during stage 6 was evident, during which parts of Britain were glaciated. In order to avoid confusion in the literature, it was argued, the name 'Wolstonian' should be retained (Gibbard and Turner, 1988, Gibbard, 1991). Others rejected the use of the term, as it was against all stratigraphic principles. If only the Wolstonian had been termed 'the Shottonian', nobody would have cared. But because the stage was named after a specific location, retaining the name is a very big problem (Rose, 1991). No such problem would ever arise concerning the Devensian, that is for sure. The type site for the Devensian is at Four Ashes in Staffs, but if ever the site was shown to be wrongly interpreted, the name of the stage could be transferred to a new type site. This cannot be done with the Wolstonian. It would be geographically silly. The mid-Pleistocene really needs close examination.

Newer Interpretations

Rejuvenated investment in construction in the 1990s led to expansion of demand for sand and gravel. In places new quarries opened, in others existing pits were extended. For Quaternary science, this was (and still is) a golden opportunity. The nature of Quaternary Science has evolved markedly over the last 15 years or so. No longer is study the rather uncoordinated effort of talented individuals or small groups whose primary interest is in one aspect of palaeoenvironmental reconstruction (look at the expanding list of co-authors in the bibliography as time progresses); big projects are undertaken by large interdisciplinary teams whose purpose is to reveal a wide range of evidence from individual sites. Such an approach may (in theory) lead to conflicting interpretation (consider the conflict of beetle and pollen evidence during the Late Glacial as outlined in Landscape Development Lecture 18). Despite this potential, the very broad range of evidence permits careful evaluation of the interpretation that can be made, consequently extremely interesting and valuable results have been obtained from such studies. A few key case studies are outlined below.

Shotton et. al. (1993), Waverley Wood Pit, Warwicks.

In this study a group of eight researchers investigated a quarry near Bubbenhall (SE of Coventry). In his earlier descriptions of the Wolston sequence Shotton had described a 'Bubbenhall Clay' lying beneath the Wolston sequence. Initially Shotton thought that the Bubbenhall clay represented the Anglian glaciation (his arguments in favour of the Wolstonian were not spurious), but he later doubted the patchy evidence (Shotton, 1983b, Shotton et. al. 1993). The pit at Waverley Wood exposed the Thrussington till, Baginton sands and gravels, and another suite of sediments beneath these gravels, including organic sediments.

The paper is really a collection of smaller research studies that are drawn together in order to build up a picture of palaeoenvironments. The stratigraphy, palaeontology (including molluscs, ostracods, coleoptera, mammalia, pollen and plant macrofossils) and archaeology of the site are evaluated. Although some of the evidence is equivocal (e.g. the pollen data) the evidence points very strongly towards a mid-Pleistocene age for the organic sequence, and one that probably pre-dates the Anglian cold stage. In addition to the above studies, amino-acid dating was undertaken, whilst again it was not conclusive an OI stage 15 age was suggested. On balance, it seems probable that the organics are part of the traditional 'Cromerian Complex' of sediments that predate the Anglian, and therefore the Baginton gravels that are incised into the sediments are probably Anglian in age, perhaps older than that. A younger age than the Anglian was not considered likely both for the organic sediments and the Baginton gravels.

I encourage you to read this paper, it is a true landmark publication. The paper represents British Quaternary Science at its best - detailed (ALL of the results are presented), considered and careful. Despite the obvious implications of the work, (Shotton is the lead author) its conclusions are a very balanced and appropriate interpretation. No study quite like this one had appeared before, but others were to follow.

Green et. al. (1996) Stoke Goldington, Great Ouse, Bucks.

This study featured contributions from 11 researchers whose specialisms included stratigraphy, sedimentology, palaeontology (of pollen, beetles, vertebrates, caddis flies and ostracods) and dating (Uranium series and Amino-acid). The sequence of sediments is complex, a sequence of gravels interspersed by 'channel' deposits (fluviatile). The latter deposits including organic sediments. Overall three gravel beds separated by two channel fills were identified. Of the three gravel beds, the uppermost is equated with the Devensian, the channel fill beneath it is equated with the Ipswichian. The pre-Ipswichian gravels represents a cold stage, with erratics derived from an eroded chalky till, possibly Anglian in age. Therefore the gravels are post Anglian, and are tentatively correlated with OI stage 6. Underneath this 'stage 6' gravel sequence the lower channel deposits are more positively correlated with OI stage 7. The lowest gravels are also considered to be post-Anglian in age.

This study hints very strongly that the apparent lack of terrestrial evidence for the gaps in the terrestrial OI record (see table 2) can be found, provided that very careful attention detail is taken. The fact that 'chalky till' appears to have been eroded during a post stage 12 cold stage to create a gravel bed may be indicative of glaciation, but is not conclusive.

Keen et. al. (1997) Frog Hall Pit, Warwicks.

Frog Hall pit is situated only 1 km from the Wolston type site and sits amongst classical Wolstonian sediments. The site consists of of two gravel sequences, interspersed by an organic mud. Above the upper gravels is a diamict, and below the lowest gravels the classic Wolston clays (from Lake Harrison) occur. The uppermost diamict is interpreted as a periglacially re-worked till, the till in question being the Oadby till. The lowest gravels are also thought to be derived from the Oadby till, as they contain clasts derived from Jurassic strata (chalky) that would not survive long distance transport. The upper gravels have a very similar lithology but are lacking in the perishable (chalky) element, and are thought to derive from a similar source as the lowest gravels, but are much younger. In this respect the sequence is similar to the Stoke Goldington sequence, but older. Therefore the sequence is interpreted thus:

On lithological grounds alone, it is clear that a post-Wolstonian, (sensu stricto) pre-Devensian glacial/interglacial cycle is represented. In addition to the sedimentology of the site, the palaeontology (inc. plant macrofossil, pollen, beetle, ostracod, mollusc and vertebrate fossils) and age of the site (as determined by amino-acid chronology) was examined. The fossil evidence pointed very strongly toward a correlation with the Hoxnian for the organic sequence, including the presence of type X and hippophae pollen. Anomalies suggested only a Hoxnian affinity, not a strict (sensu stricto) Hoxnian assemblage. A close resemblance between the Frog Hall organics and the Nechells and Quinton organic fossil assemblages is noted.

The paper further recognised other work that indicates that some 'Hoxnian ' sites could be as young as OI stage 9, whilst others represent stage 11. The upper gravels of the Frog Hall sequence may correlate with stage 6 gravels found in the Warwickshire Avon basin, but it cannot be proven. The amino-acid dates strongly suggest a stage 9 age for the organic muds, and therefore the Oadby derived gravels below the organics must be OI stage 10 or earlier. The Frog Hall sequence positively shows that the classical OI stage 6 Wolstonian glaciation is an incorrect interpretation of the evidence. The Wolstonian sequence belongs to stage 10 or earlier.

Current Understandings.

The Wolstonian type site has been wrongly assigned to OI stage 6. Sedimentological study of both the Dunsmore Gravels (that cap the Wolston sequence) and the Baginton gravels has equated both sequences with gravels of Anglian (or perhaps pre-Anglian) age. It seems likely that the Wolston type site is correlated with an Anglian (sensu stricto) glaciation (i.e. OI stage 12). The Waverley Wood evidence suggests a possible stage 14 age for the Baginton sequence, although a stage 12 age is not beyond reason. A stage 6 age seems unlikely. The evidence from Stoke Goldington and Frog Hall hints at cold conditions during stage 6, with ice proximal to the Midlands but not proven. The Frog Hall deposits positively demonstrate that an OI stage 6 'Wolstonian' glaciation did not exist, since the type site predates OI stage 9. So what of the Wolstonian?.

To be honest, this is no longer an issue. The QRA field guide for Norfolk & Suffolk (Lewis et al., 2000) makes only scant reference to the 'Wolstonian' problem. This is not to say that there aren't difficulties in interpreting the either the stratigraphy or the glaciological processes responsible for sedimentation in East Anglia (read Whiteman, 2000). The main problem of the Wolstonian is the use of the term itself (see Gibbard and Turner,1988; Gibbard,1991 and Rose,1987;1991)

My thoughts.

The strangest anomaly is the most firmly dated sequence, that of Frog Hall. The abstract for the paper points out that the minimum age for the pre-organic sequence (the Wolstonian deposits) is stage 10, "...and is therefore close in time to the Anglian cold stage". (Keen et. al. 1997, p 183). This is the equivalent of saying that mammoth bones dating from the mid-Devensian are close to being Wolstonian in age! Bowen (1999) pronounces the death of the Wolstonian (sensu stricto) as a result of the Frog Hall findings, however, a problem remains.

Shotton has long argued that the correlation of the Dunsmore and Baginton gravels with Anglian (sensu stricto) deposits from East Anglia is erroneous. Furthermore, the Frog Hall evidence hints at a stage 10 age for the Wolston sequence. The Stoke Goldington sequence also hints at this interpretation. Whilst the Wolstonian (sensu stricto) sequence may not represent an entire stage 6 glaciation, it may represent and entire stage 10 glaciation. The Wolstonian (sensu lato) may exist as a real cold period, but just needs to be re-assigned to a new OI stage, stage 10. The issue as yet is unresolved, since the Waverley Wood evidence does suggest that the Wolstonian could be as old as stage 14. We also do not have a name for a stage 6 glaciation that almost certainly occurred. How do we deal with the mid-Pleistocene problem? Answers on a post-card pleae, to anyone but me.

Next Week...

Back in the 1970s, Bowen had an answer. He was working on the Quaternary of Wales, and he decided that the way to work out the Quaternary of Wales was to look at the Welsh evidence, and ignore the English evidence entirely. Instead of shoehorning the Quaternary of Wales into a pattern determined in England, which itself was a pattern shoehorned into the accepted European story, he would determine the Quaternary history of Wales. If the story did not match that of England, the next task was to find out why, and not to revise the Welsh sequence because it did not fit. This was a radical and brilliant approach that led to the re-writing of the Quaternary of the UK.

Nowadays Bowen (1999) is beginning to argue for a total scrapping of traditional interpretations of the Quaternary; but that, for the moment, is taking you a step too far. The latest thinking reflects some of the issues I raised above, and needs to be followed up

References and Further Reading.

Allen, P. et. al. 1991. ‘The Tills of Southern East Anglia.’ IN: Ehlers, J. et.al.. (Eds.) Glacial deposits in Great Britain and Ireland. Balkema, Rotterdam. pp. 255-278.
Bowen, D.Q. et. al. 1986. ‘Correlation of Quaternary Glaciations in England, Ireland, Scotland and Wales.’ IN: Šibrava, V. et. Al. (Eds.) Quaternary Glaciations of the Northern Hemisphere. Quaternary Science Reviews 5. PP 299 - 340. Pergammon, Oxford.
Bowen, D.Q. 1999. A Revised Correlation of the Quaternary Deposits in the British Isles. Geological Society Special report NO. 23. Geological Society, Bath.
Cox, F.C. 1981. ‘The ‘Gipping Till’ Revisited.’ IN: Neale, J. and Flenley, J (eds). The Quaternary in Britain: essays, reviews and original work published in honour of Lewis Penny on his retirement. Pergammon, Oxford.
Ehlers, J. & Gibbard, P. 1991. ‘Anglian Glacial Deposits in Britain and the Adjoining Offshore Regions.’ IN: Ehlers, J. et.al.. (Eds.) Glacial deposits in Great Britain and Ireland. Balkema, Rotterdam. pp. 17-25.
Ehlers, J. et.al. 1991. ‘The Glacial Deposits of North-western Norfolk..’ IN: Ehlers, J. et.al.. (Eds.) Glacial deposits in Great Britain and Ireland. Balkema, Rotterdam. pp. 223-232.
Green, C.P. et. al. 1996. ‘Pleistocene deposits at Stoke Goldington, in the valley of the Great Ouse, UK.’  Journal of Quaternary Science 11(1) pp. 59-87.
Gibbard, P. L. and Turner, C. 1988. ‘In Defence of the Wolstonian Stage.’ Quaternary Newsletter 54, pp. 9-14.
Gibbard, P. L. 1991. ‘The Wolstonian Stage in East Anglia.’ IN: Lewis, S.G et al. (eds) 'Central East Anglia and the Fen Basin. QRA, London. pp 7 - 13.
Gibbard et. al., 1992. ‘Early and Middle Pleistocene Correlations in the Southern North Sea Basin.’ Quaternary Science Reviews, 10 pp. 23-52.
Jones, R.L. and Keen D.H. 1993. Pleistocene Environments in the U.K. Chapman and Hall, London.
Keen, D.H. (ed.) 1989. West Midlands Field Guide. Q.R.A. Cambridge.
Keen, D.H. et. al., 1997. ‘Middle Pleistocene deposits at Frog Hall Pit, Stretton on Dunsmore,Warwickshire, English Midlands and their Implications for the Age of the Type Wolstonian.’  Journal of Quaternary Science 12(3) pp. 183-208.
Lewis S.G. & Maddy, D. 1997. The Quaternary of the South Midlands & the Welsh Marches Field Guide. QRA, London.
Lewis, S.G et al. 1991 (eds) Central East Anglia and the Fen Basin Field Guide. QRA, London.
Lewis, S.G et al. 2000 (eds) The Quaternary of Norfolk & Suffolk Field Guide. QRA, London.
Mitchell, G.F. et. al., 1973. A Correlation of Quaternary Deposits in the British Isles. Geological Society of London Special Report 4.
Perrin et. al., 1973. ‘Lithology of the Chalky Boulder Clay.’ Nature. 245 pp.101 - 104.
Perrin et. al., 1979 ‘The distribution, variation and origins of pre-devensian Tills in Eastern England.’ Philosophical Transactions of the Royal Society of London, 287 (series B), pp. 535-570.
Rose, J. 1987. ‘The Status of the Wolstonian Glaciation in the British Quaternary.’ Quaternary Newsletter 53, pp. 1-9.
Rose, 1989. ‘Tracing the Baginton - Lillington Sands and Gravels from the West Midlands to East Anglia. IN: Keen, D.H. (ed.) West Midlands Field Guide. pp. 102 -110. Q.R.A. Cambridge.
Rose, J. 1991. ‘Stratigraphic basis of the 'Wolstonian Glaciation', and retention of the term Wolstonian as a chronostratigraphic stage name - a discussion.’ IN: Lewis, S.G et al. (eds) Central East Anglia and the Fen Basin Field Guide. QRA, London. pp 15 - 20.
Shotton, F.W. 1983a. ‘Observations on the Type Wolstonian Glacial Sequence.’Quaternary Newsletter 40, pp. 27-36.
Shotton, F.W. 1983b. ‘The Wolstonian Stage of the British Pleistocene in and around its Type Area of the English Midlands.’ Quaternary Science Reviews 2, pp. 261-280.
Shotton, F.W. 1986. ‘Glaciations in the United Kingdom.’ IN: Šibrava, V. et. al. (eds.) ‘Quaternary Glaciations of the Northern Hemisphere’. Quaternary Science Reviews 5. PP 293 - 298. Pergammon, Oxford.
Shotton, F.W. 1989. The Wolstonian Sequence and its position within the British Quaternary Sequence.’IN: Keen, D.H. (ed.) West Midlands Field Guide. Q.R.A. Cambridge.
Shotton, F.W. et. al., 1993. ‘The Middle Pleistocene deposits of Waverley Wood Pit, Warwickshire, England.’  Journal of Quaternary Science 8(4) pp. 293-325.
Straw, A. 1982. ‘Certain facts Concerning the Wolstonian Glaciation in Eastern England.’ Quaternary Newsletter 36, pp. 15-20.
United Kingdom Contribution to the International Geological Correlation Programme; Project 24, Quaternary Glaciations of the Northern Hemisphere Group. (1983) ‘Interglacials after the Hoxnian in Britain.’ Quaternary Newsletter 39, pp. 19-24.