310 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



prevailing direction from N. to S., agreeing with that of the valley ; 

 but such a parallelism between the furrows in the surface of the 

 chalk and the nearest valley does not hold as a general rule ; for 

 in a space that was subsequently cleared, less than 20 yards from 

 that shown in the diagram, the direction of the furrows was E. 

 and W. Upon the whole, however, the north and south furrows 

 seem to be the deepest. 



The deepest of the furrows shown in the diagram, which was 

 p, was about 3 feet wide, and 1 foot deep : the next furrow, q, 

 was 6 inches wide and 3 deep ; and, for the length of 2 or 3 yards, 

 was as clean cut as a gutter-tile. It led to a circular cavity, r, 

 3 feet in diameter, which looked like the mouth of a pipe ; but, 

 on removing the sand, it was found to be only 1 foot deep in the 

 centre. The rest of the furrows were broader, shallower, and less 

 regular than the two former, and were lost in a large irregular 

 cavity, not visible at my first visit to the pit, but afterwards ex- 

 posed to view in a vertical section, passing through the line e p, 

 about 12 feet to the south of the line ab. 



The hollow (see Fig. 8.) thus laid open was about 11 yards 



Fig. 8. 



West 



1. Solid chalk. 



p. Pan, or ferruginous breccia. 



2. Sand, black towards the bottom, yellow towards the top. 



3. Whitish sand. 



wide, and was divided by a ridge of chalk into two cavities, which 

 were respectively 21 and 12 feet wide., and 3 and 7 feet deep. 

 The bottom of this hollow, like the surface of the chalk generally, 

 was lined with the pan ; above this, within the hollow, was sand, 

 blackish towards the bottom, but yellow towards the top. Over 

 this and over the Pan beyond the limits of the cavity, was a whitish 

 sand. 



In other parts of the Rackheath pit, several sections of deep 

 pots were visible ; and one of the most remarkable of these is 

 represented in Fig 9. 



" Core" is the term given by the workmen to the column of un- 

 stratified, tenacious, gravelly loam, which is sometimes found over 

 a "pot" in the chalk, rising through and traversing the regularly 

 stratified and alternating bands of sand, gravel, and clay, belonging 

 to the crag and overlying the chalk. One of these cores, pro- 

 jecting in relief above the strata of the crag, is represented in the 

 annexed diagram. On one side, the laminae of stratification bend 



