Villages 109 



Clay which overlies the Chalk on the top of this upland area (see Fig. 29), and 

 which, most probably, was covered with deciduous woodland (see Fig. 17). 

 The outstanding feature of this district to-day is the considerable area, 

 running north-east — south-west, that is villageless and also streamless until 

 the River Bourn is reached in the south. This belt is the wide strike 

 exposure of the porous chalk country. In its completely dry character lies 

 the explanation of its luipeopled state. To the south, near the Bourn and 

 Granta rivers, come the vdley villages. Some of them have "ford" 

 terminations; in each case, the precise site was determined by rising ground 

 safe from flood. In the east, very near to the 300 ft. contour and between 

 woodland and open country, are the upland villages. Until recendy, 

 some of these villages have used for domestic purposes the surface rain- 

 water that drains into hollows on the impervious clay; wells have to be 

 sunk so deep before reacliing the bottom of the chalk, that they are 

 expensive items. Along the edge of the clayland, then, most of the upland 

 villages are situated. The advantages of a site on the edge of the wood, 

 rather than within it, can be readily appreciated. Finally, the 50 ft. contour 

 marks, roughly, the junction between chalk and fen. Along this line, 

 springs gush out from beneath the chalk, and so, following the fenland 

 edge, is a string of eleven villages from Burwell in the nordi to Cherry- 

 hinton in the west. To the north-north-west of these fen-Hne sites, recti- 

 linear watercourses indicate the drained fen. There, on the drier spots, 

 are other marginal villages; a few spot heights have been inserted. 



South-western Cambridgeshire. Fig. 25 gives details of villages and streams 

 in the country to the west of Cambridge town, and it covers the same acre- 

 age as Fig. 24. The Cam Valley occupies the south and east of the map. In 

 the middle west is a small plateau over 100 ft. above sea-level; diis contains 

 two ridges (above 200 ft.) that run east-west to form the boundaries of the 

 Bourn Brook Valley. The surface of the plateau is almost entirely composed 

 of clay of various kinds, mainly Boulder Clay and Gault, but also Kimeridge 

 and Oxford Clays (see Fig. 29) ; presumably it was wooded in early times.' 

 Generally speaking, the plateau forms the watershed between the tribu- 

 taries of the Ouse and those of the Cam; many of the streams marked on 

 the map are only a foot or two in breadth, but, even so, their presence 

 shows this to be a district quite different from that on the eastern side of the 

 Coimty. 



The top of this plateau is almost villageless. The villages are set around 

 the edges. The elements important in their distribution seem to be as 

 follows : 



(i) The valley sites of the Bourn Brook and of the Cam explain 

 ' For Domesday Woodland, see Fig. 17 above; for earlier evidence, see p. 103. 



