SINKING OF THE LAND IN CAMBRIDGE 405 



cut off by timber and puddle and did not affect the water in 

 the hole sunk for the foundation. But the water in the hole 

 rose above the level of the water in the river, proving that 

 there is a passage of water down valley through the gravel 

 in ancient channels, independent of the water in the exist- 

 ing bed of the stream, and confirming the generalisations 

 arrived at above. 



This subsidence was not sudden, but part of a continuous 

 or intermittently repeated depression, which we can trace back 

 to pre-glacial times at any rate. 



When the deep drain was cut in 1895 along the road in 

 front of Jesus College the following section was seen (fig. 11): 



Macadamized road. 



Made ground with fragments of 13th century buildings. 



Sand and gravel. 



Tusk of ElepJias primigenius. 



~'- : _ - Sand with much water. 

 f* i __ Bottom of drain at 28 ft. 



. ^.JT. Running sand proved with jumper to 31 feet, no gault 

 touched. 



Fig. 11. Section seen in roadway in front of Gate of Jesus College during 

 excavations for new drainage, Oct. 7, 1895. Scale 8 feet to 1 inch. 



The Bench Mark at Jesus Gate is 31*2 feet above O.D., and 

 the ground falls to 26'3 feet on the path along the edge of Butt 

 Green east of East House. But at the bottom of the drain 

 running sand was proved with a jumper to 31 feet and the gault 

 not touched. On the higher ground at Barnwell the base of the 



