Geoscience Reference
In-Depth Information
Searles V. Wood, Jun. is generally recognised as establishing a systematic study
of glaciology in eastern England-East Anglia in particular. He was convinced that
many of the problems in understanding the nature of glacial geology could only be
resolved by mapping its deposits, an undertaking which, up to that time, had never
been attempted in England—let alone in any other country. Wood therefore
undertook the monumental task of mapping these deposits on a scale of 1 inch to
1 mile, from the Wash to the Thames valley, and from central England to the
Norfolk-Suffolk coast, covering an area of 2,000 square miles.
The following 6-7 years were devoted to examining these deposits with Har-
mer, who had taken up the challenge set by his colleague with characteristic zeal
and industry. Together they undertook this large-scale mapping project to show the
distribution of Pliocene and Pleistocene deposits in eastern England, Wood cov-
ering the drifts of Suffolk and Essex and Harmer those of Norfolk. By 1868 the
work was sufficiently advanced for a geological map to be presented illustrating
the distribution of pre-glacial and glacial beds over an area of 2,000 square miles.
Wood and Harmer embodied the results of their study in the memoir, An
Outline of the Geology of the Upper Tertiaries of East Anglia together with a map
(reduced form of the original, with a few corrections) and various sections of the
Crag District (Wood Jun. and Harmer
1872
-1874), the whole work being included
in the 1872-1874 volume of the Palaeontographical Society, Supplement to the
Monograph of the Crag Mollusca, with Descriptions of Shells from the Upper
Tertiaries of the East of England (Fig.
3.6
), which remains one of the classic texts
in the literature of geology (Wood Sen.
1872-1874
).
The definitive distribution of chalky boulder-clay was established by Wood in
1880 (and later Harmer). It was concluded that an ice stream moved from the
North Sea across parts of the Lincolnshire Wolds, being deflected southwards by
another ice stream from the Vale of York, and then fanned out into East Anglia and
central England. A further ice stream of the same glaciation was believed to have
entered Norfolk across the present north coast of the county coming into contact
with the North Sea Drift (Cromer Till and Norwich Brick-earth).
Harmer believed that the glacial deposits of East Anglia were initially laid
down due to the invasion of the region by the western edge of a large ice sheet,
such as exists in Greenland today, which originating on the Scandinavian uplands
(probably standing at a higher level than today) filled the basin of the North Sea
and overflowed across the north European plain. The contorted drift of its moraine
profonde (a term used at the time for ground moraine) may definitely be traced
from the coast at Cromer as far as sites in south Norfolk and Suffolk, such as
Sotterley, Withersdale Street, Scole and Bury St Edmunds; it may also have
extended even further south, as well as partly spreading over the Fenland.
