SINKING OF THE LAND IN CAMBRIDGE 403 



Fig. 9. Diagram Section from Park Street to Victoria Bridge. 

 a. Gault. 6. Gravel. c. Alluvium. 



Jesus Ditch and the girls' school at the bottom of Park Street 

 (fig. 9), the following section was seen : 



Surface soil. 



Peaty silt. 

 Grey clay. 

 Layers of gravel.. 



Alluvium 17 feet. 



The layers of gravel in c appeared to be a wash-down from 

 the adjoining terrace of more ancient gravel 6, and were full of 

 water. In the silt I found a few fragments of black pottery, 

 the exact age of which it was difficult to determine 1 . A little 

 nearer the river Mr Bullock sunk an artesian well into the 

 Lower Greensand which threw up water to a height of 4 feet 

 above the level of the ground. 



In the course of further excavations along the line of Park 

 Parade he found an old river channel running to a depth of 

 27 feet below the surface of the common. The level of the 

 river below the lock is only 20 feet above O.D. 



The section exposed in digging the foundations of the new 

 Racquet Courts in Thompson's Lane in 1892 is shown in fig. 10. 



I saw a large limb bone of Bos and specimens of Planorbis 

 corneus at a depth of 22 feet in the gravel and silt, and was 

 informed that bones, pottery, and oyster shells had been found 

 in large quantities in the upper part of the section. 



I was told also that the deepest part of the trough was 

 about the middle of the east room, and that the old channel 

 seemed to bend round to a more southerly course towards the 

 south-west corner. It is not improbable that this may be part 

 of the same ancient channel which is shown in the section 



fig. 9. 



1 See Proc. Camb. Ant. Soc. Vol. vin. 1892, pp. 44, 45, PI. 3. 



