Geoscience Reference
In-Depth Information
The identification of at least two layers of boulder-clay in Norfolk, separated by
interglacial sands, demonstrated that the chronology of the Ice Ages, or the
Pleistocene, was more complex than had previously been proposed by the Swiss
geologist, Louis Agassiz (1807-1873) in the 1830s. This finding preceded the
better known views of the Scottish geologist, James Geikie (1839-1915) who also
had suggested that instead of one single advance and retreat, the Pleistocene had
been marked by a series of alternating glacial and interglacial stages. Harmer noted
that a pit near the Trowse railway junction (one mile south of Norwich) which
exposed a glacial deposit of an unstratified whitish clay containing much chalk
debris and occasional quartzose erratics, fully provided evidence for this concept
(Harmer
1867a
,
b
) (Fig.
3.25
).
Fig. 3.25 P680270 (1907) Harmer's geological excursion to Norfolk with a member of the
group at a site illustrating distinctive layers of glacial sands and gravels. (CP13/050 Reproduced
by permission of the British Geological Survey NERC. All rights reserved)
