part 3] PLEISTOCENE DEPOSITS AROUND CAMBRIDGE. 21T 



Two pits belonging to Messrs. Swann have been worked during 

 the last few years close to the Traveller's Rest Inn. These I shall 

 speak of as the North and South Pits : the former is now closed. 

 L have studied the sections continuously since 1911, and obtained 

 a considerable number of implements from them, which will be- 

 noticed presently. 



Some measurements will give an idea of the extent of the sections. 

 The North and South Pits lie side by side, with an interval of a 

 few yards between them. Continuous sections were exposed in the 

 south-western faces of the two pits, and are still seen in the southern 

 pit. The continuous section of this pit is about 130 yards long, 

 that of the northern pit having been about 30 yards. The total 

 length of the southern pit at right angles to this face is approxi- 

 mately 100 yards. 



A very tine section is now (1919) exposed on the south- western 

 face of the South Pit. of which the following is a generalized 

 sketch, details of which are copied from photographs kindly taken 

 for me by Mr. R. H. Rastall (fig. 2, p. 212).^ The gravel varies, 

 in thickness from IS feet at the two ends of the section to 14 feet 

 near the centre, to which the Gault floor rises gradually from 

 each end. 



The Gault is usually unaltered, save for a slight weathering for 

 an inch or two at its surface : but in one place in the North Pit 

 a puddled mass of Gault occurred below the basal gravel-seam, and 

 in this puddled material were nodules of ' race ' similar to some 

 (described later) in a deposit not far away from the gravel-ridge. 



In most sections in the two pits the gravel is readily divisible 

 into two series, of roughly equal thickness, though in the northern 

 corner of the South Pit the upper series was almost certainly absent. 

 a matter of some importance, as will be noted when dealing with 

 the implements. 



The lower series is evenly bedded, and the upper more irregularly 

 bedded, often with thick masses devoid of bedding. The two 

 series will be spoken of as -the lower evenly-bedded' and the 

 'unevenly-bedded' series. The latter rests uneonformably upon 

 the former, and is in many places marked by channels of erosion 

 at the base, as shown in the section. In addition, there are other 

 channels due to subterranean erosion. The former, on the whole 

 run parallel with the long axis of the ridge, the others more or 

 less at right angles to it, down the slope towards the western 

 valley. The significant feature of these channels of either type 

 is that the upper parts of the latter type, and often also of the 

 former when they arc at the top of the succession, are rilled 

 with loam. 



The usual ferruginous 'pipes' occur at the summit of the deposits 

 immediately beneath the subsoil. They an- quite distinct from the 

 loam-channels. In the north-eastern part of the pits the loam- 

 channels also extended upwards to the subsoil. But, as the pit 

 is cut back, a new set of deposits has appeared, consisting of well- 

 bedded sand and gravel 2 to 3 feet thick. Beneath these we find 



