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The Anglian ice advance was the most extensive in Britain. It originated in northern Britain and
should have run directly out into the Nortli Sea basin. However, ice build up had started earlier
in Scandinavia and the basin was nearly filled with ice from that source as far south as north
Norfolk. The British ice, as a consequence was diverted to run southwards between the
Scandinavia icc and Britain. Details of its route arc not clear and are in contention. There is
fragmentary evidence that it covered eastern England depositing a lower till at places such as
Kettering in Northamptonshire, various points in Norfolk and Suffolk, and just possibly the
Chelmsford area. From studies of orientations and lithologies of stones in the till, a case can be
made for an initial advance southwards that covered eastern England and adjacent parts of the
North Sea basin, but once clear of the Scandinavian ice was able to spread out southwards and
eastwards over East Anglia (Fig. 3) (Rose, 1992). If the premise is correct, icc could have
entered Essex with a strong west to east component to its direction of travel. Later the travel
path appears to have centred more on the North Sea Basin, with icc passing through the low land
of the Wash and Fens and so would have entered Essex from the north or NNW.
At Newney Green, Great Waltham and Broomfield, there is some evidence to support an early
ice advance from the west or WNW (Whiteman, 1987; Whiteman, in Allen et ai, 1991). There
is a brown lower till (Newney Green Member) in which the elongate stones are aligned
predominantly WNW-ESE. though at Broomfield the stones are aligned WSW-ENE (Fig. 4).
Unfortunately, patterns of preferred stone orientations in till can be interpreted in two ways. If a
glacier is moving freely, it experiences extending flow and elongate stones tend to align with the
direction of flow during deposition. Hence the evidence above could be used to support glacier
movement from the west or WNW. However, if the glacier's progress is hindered, then the ice
compresses and the stones rotate so their long axes are transverse to the direction of flow.
Compression can occur as a glacier moves uphill, but also where the subglacial water which
lubricates the base of the glacier is lost to the underlying sediment. In this case, basal friction is
increased, causing compressive flow. It quite likely that there was a loss of water to the
underlying early Thames gravels, with consequent compressive flow. In this case, the preferred
orientations could be linked with movement from the north or NNW. Unfortunately, the range
of stone types is not sufficiently sensitive to determine the direction of ice travel. If anything, as
they are mostly of local origin from the underlying gravel, they indicate that the ice was
compressive and shearing the substrate into its basal zone. The lower till is more sandy than at
higher levels, again suggesting incorporation from the underlying gravel. The brown colour of
the lower tills is probably due to oxidation of the iron-content due to the sand making the till
more permeable to water and air. For these various reasons, compressive flow of ice arriving
via the Wash and Fens is the accepted explanation for the west-east component of the
orientations, though the other possibility is not entirely dismissed.
The higher till (Great Waltham Member) shows a variety of orientations from northwest-
southeast to northeast-southwest, i.e. there is a strong north-south component, linking with a
northerly approach of the ice (Fig. 3) (Whiteman, 1987; Whiteman, in Allen et al., 1991). The
body of the till is clay-rich and grey in colour, reflecting iron in the till remaining in the reduced
state. The upper part of the till, or all of it where it is thin, may be a dull yellowish-brown due to
weathering. The clay contains microfossils linking it with the Jurassic outcrops of the Wash and
Fens area. The stone content also provides links to the north, such as Red Chalk from the area
between Hunstanton and Humberside and Rhaxella chert from the Helmsley area of north
Yorkshire. Local material is far less common in these tills. These tills are associated with
extending flow of an icc sheet approaching from the north. The lower till may have provided
sufficient of a seal over the gravels that the base of the ice was now better lubricated.
Essex Naturalist (New Series) 16 (1999)