Geoscience Reference
In-Depth Information
Harmer's meeting by chance with the geologist, Searles Valentine Wood,
Junior, 1830-1884 (son of the renowned palaeontologist, Wood Senior
1798-1880) on Mundesley beach and their subsequent friendship proved to be
most beneficial to Harmer by enhancing his geological studies. For example, in the
early 1870s they jointly presented a detailed account of the Red Crag:
The physical structure of the Red Crag is unlike that of any other formation known to us,
ancient or modern. The more considerable portion of it is formed of a succession of beds,
varying from two or three, to nearly twenty feet in thickness, each of which consists of
laminae of sand and shells, inclined at a high degree to the horizon. This structure is
altogether different from the well known one of false bedding, which also exists in some
parts of the Red Crag, especially in that under which the phosphatic nodules are worked,
and the two forms of bedding pass more or less into each other. This oblique lamination
may be traced (as, for instance, in Bawdsey Cliff) for a considerable distance in a constant
manner, without shading off into horizontal stratification or passing into false bedding
(Wood Jun. and Harmer
1872
-1874).
In providing one of the best exposures of the Red Crag in the country, Bawdsey
Cliff has now been declared a Site of Special Scientific Interest (SSSI) by Natural
England.
Harmer stated that the various exposures of the Red Crag group themselves in a
horizontal rather than a vertical sequence, with the older deposits occurring
towards the south and the newer ones to the north or northeast. He continued that
when they are traced from Walton in the southwest to Butley in the northeast, the
deposits gradually assume a more boreal and recent character. The earliest indi-
cation of the conditions which prevailed during Red Crag times was afforded by a
unique and now invisible bed of unstratified grey silt at the base of the Walton cliff
section as described by Wood, Jun., in 1864 in which molluscs were found in situ
where they had lived and died (Harmer
1910b
).
On a visit to the Netherlands Harmer found that there was an area immediately
south of the Hoek van Holland which appeared to be experiencing marine and
meteorological conditions similar to those which occurred along the East Anglian
coast during the Red Crag period, that is, strong onshore prevailing winds but
southwesterly in direction rather than easterly—as in the earlier period. He found
that a former bay or inlet was nearly choked with shelly sand that was still
accumulating on the edges of shoals and in channels formerly occupied by the
River Maas; the deposits were often bedded at a high angle with the stratification
dipping in different directions as it followed the sinuous windings of the banks. As
such drift only now occurs rarely on the shores of East Anglia, its accumulation in
such abundance during the Crag period indicates, Harmer believed, that the pre-
vailing winds were predominantly easterly associated with storm tracks aligned at
that time further south than they generally occur today. Such evidence of major
changes in the wind flow since the Pliocene epoch led Harmer to his pioneering
reconstruction of past circulation patterns and study of palaeometeorology.
The identification of the Red Crag by the English palaeontologist, Edward
Charlesworth (1813-1893) in 1835 as a separate stage of East Anglian Crag was
followed by studies of later geologists, including Harmer, into this Pliocene