GEOLOGY 
rocks and fossils drifted from a distance, including basalt, porphyry, 
granite, slate, encrinital limestone, red sandstone, rocks and fossils from 
the Coal Measures, Lias, and Oolites, and ironstone from the Lower 
Greensand, etc. Major Cooper has also found in it ‘a good red-tinted 
example of Pectunculus glycimeris . . . apparently from the Crag,’ and ‘a 
patella from one of the hind legs of Cervus elaphus.’ 
This gravel appears from its constituents to be of glacial origin, 
but differs somewhat from the Middle Glacial sands and gravels below 
or intercalated with the boulder clay in Hertfordshire and elsewhere. 
It may possibly represent the plateau or ‘cannon-shot’ gravel which 
overlies the chalky boulder clay in many places in the eastern counties, 
and which ‘ may perhaps have resulted in part from the melting away 
of the ice-sheet that formed the clay.’* It is difficult to account for the 
presence in it of a bone of the red deer, but that may have been derived 
from beds of later Pliocene age, and it does not necessarily indicate a 
non-marine origin for the gravel.’ 
Bedfordshire was certainly beneath the sea at the close of the 
Glacial epoch, if not during the deposition of the boulder clay, and 
before the land again rose milder conditions had set in. There are 
evidences of successive stages of elevation before the present level was 
attained and the British Islands were finally cut off from the continent 
of Europe. It was during this period that much the greater part of our 
present fauna and flora was introduced from the continent, and that early 
man reached Britain, for his advent must have preceded the formation 
of the Straits of Dover by which England was finally severed from France. 
It was also during this period of elevation that the present river-system 
of Bedfordshire originated, except in the case of those streams which 
took the course of existent or pre-Glacial valleys not entirely filled up 
by boulder clay. Snow-fields had not altogether disappeared from 
Britain, for as our present mountainous districts rose higher and higher 
after their submergence to a depth of at least 2,000 feet, they were 
again covered by ice and snow, the glaciers from which have left ice- 
grooved rock-surfaces and moraines as evidence of their passage down 
the valleys. In the lowlands the rainfall was probably copious, and as 
the rivers in the midland and eastern counties flowed over boulder clay, 
percolation would be small and most of the rain which fell would flow 
off the surface and make the rivers large and swift and the rate of denu- 
dation much greater thanit isnow. This is the period of the formation 
of the older river-gravels, much of the material of which was derived 
from the erosion of the boulder clay, the clay being carried down the 
swift-flowing streams in suspension, leaving sheets of gravel, and being 
deposited as alluvium when the current became less swift. 
The river Ouse in its passage across the county flows in a valley 
1-H. B. Woodward, Geohgy of England and Wales, ed. 2, p. 510. : 
2 Since the above was in type we have seen, near the summit of the hill west of Toddington, 
exposures of this bed of gravel and sand which we consider to be a local development of the boulder 
clay (the higher part here) into which the bed merges. 
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