Vol. 60.] IMrLEMENTlFEROUS SECTIONS AT WOLVERCOTE. 121 



peat and sand, not more than 2 inches thick. Mr. Clement Reid, 

 F.R.8., examined a portion of it, and rightly described it not as 

 originally having been a land-surface with vegetation growing upon 

 it (which I had at first thought it to be), but as a water-surface, which 

 had caught and deposited in a backwater a number of plant-remains 

 floated down the stream. It is material to an examination of the 

 bed that this layer, now below 15 feet of soil, must at the time of 

 its formation have been at the surface of the water. Peaty sub- 

 stance would not form at the bottom of a flowing stream. 



The 15 feet of strata between the gravel and the present surface 

 have a different appearance. They are conformable to the gravel 

 below, and have been laid down by water, as is manifest from the 

 long and even lines of deposition. .But there is no gravel and little 

 sand, only successive layers of mud or clay — sometimes blue Oxford 

 Clay, very little altered, at others the layers are coloured yellow and 

 red by the oxidation of iron. The whole upper part has the appear- 

 ance of having been laid down in a lake, or in a large river-pool, 

 but not in a running stream such as deposited the gravel below the 

 lakes. Prof. Phillips 1 wrote, no doubt correctly, of lakes which 

 had existed and disappeared in the earlier stages of the formation 

 of the Thames Valley. The position at the head of the gorge at 

 Goring is one that naturally suggests a prehistoric lake ; and at the 

 present day it forms a lake in times of flood. The Wolvercore site 

 in its present condition bears no resemblance to one where a lake 

 would be likely to form, as there is a natural fall in the ground to 

 the eastward, the direction of the stream, and there are no approach- 

 ing spurs of higher ground on either side. If we consider that the 

 beaver was a tenant of the valley in Pleistocene times, we have, I 

 think, no improbable reason for the surface of the stream to have 

 risen in height, and for the formation of a pool instead of a running 

 stream. Beavers' dams are sometimes 300 yards in length, and a 

 barrage of this size would completely account for the change visible 

 in the section. Had I found fossil remains of the beaver in the 

 bed, I should have offered this explanation of the upper part of the 

 section without any hesitation. I have, however, found neither 

 beaver nor anything else in this portion of the section ; nor have I 

 seen remains of the beaver except in a Neolithic peat near Paringdon. 

 At the same time, the beaver was a Pleistocene creature, and his 

 influence in altering a river-landscape was probably at that epoch 

 little interfered with by man. Even in later times the influence of 

 the beaver should be looked for ; probably many flat plains upon 

 the reaches of our rivers owe much of their form to the handiwork 

 of this busy creature in the Neolithic and early historic ages. 



To complete the description of the river-bed, it should be added 

 that the Oxford Clay beneath the gravel is curiously pitted. This 

 gravel does not lie in a horizontal plane above the clay, but Alls 

 innumerable contiguous pits measuring about 3 feet in diameter 

 and 1 foot in depth. The clay beneath the deposit which I have 



1 ' Geology of Oxford & the Valley of the Thames ' 1871, pp. 462-63 & 468. 



