178 REPORTS ON THE STATE OF SCIENCE. — 1915. 



and counterscarp of the fosse. This part of the ditch being near the 

 road had been used as a receptacle for all manner of rubbish and 

 pots and pans, all of which had in the first place to be cleared, together 

 with the stumps of many bushes. Then, with the owner's permission, 

 fom- young trees of some fifteen years' growth were- removed from 

 this position and transplanted. Afterwards in the removal of the 

 silting, even at considerable depths, the work was much impeded not 

 only by the roots of the bushes and young trees, but also by those 

 of many of the larger trees growing on the causeway. 



The first week was devoted to the removal of comparatively recent 

 silting at the end of the fosse and along the eastern margin of the 

 causeway down to the level of the surface of the silting at the east end 

 of the cutting. On the completion of this work the true and enormous 

 dimensions of the upper margin of the fosse and its termination against 

 the side of the causeway was revealed. 



From the summit of the ancient entrance (eastern margin) to the 

 brink of the true fosse — a distance of about 18 ft. — the solid chalk was 

 found to fall gradually, with slight ledges cut at intervals as previously 

 m.entioned. From the brink, the solid chalk profile of the fosse — in 

 other words the eastern face of the causeway — dipped downwards at 

 an angle of 61°, its upper margin being nearly straight (and square 

 with the line of the fosse), with a slight concavity towards the west. 

 Following the brink of the fosse in this part it was found that its 

 upper margin had a maximum width of 45 ft. From the true margin of 

 the fosse at the west end a depth of 6'5 ft. of silting had to be removed 

 before the level of the surface of the silting at the east end of the cutting 

 was reached. 



In re-excavating the successive strata the same arrangement of 

 concave seams of silting were met with as in the fosse cuttings described 

 in the former reports. Almost needless to say, there was found to be 

 a greater depth of mould and mixed silting at the west end than at the 

 east end of the cutting, but an average section of the fosse showing 

 the nature of the silting cannot be delineated until the remaining layers 

 of silting have ultimately been removed.* It is estimated that about 

 fiye-eighths of the silting in this large cutting were cleared out at the 

 close of the season's work. 



After an infinite amount of patient labour a length of 4-25 ft. of 

 the original floor of the fosse, at the west end and against the face of the 

 solid causeway, was uncovered at the enormous depth of 29-5 ft. below 

 the brink of the fosse, vertically measured, that is 35 ft. below the 

 top of the ancient causeway and approximately 54-5 ft. below the 

 present crest of the vallum. Even with these dimensions it is difficult 

 to realise the magnitude of this part of the re-excavated fosse without 

 visiting the site. 



The bottom of the fosse in the part already uncovered was found 

 to be fairly level, the width on the line of the causeway being 13 ft. 

 The lower 7 ft. of the end-wall was inclined at an angle of about 71°. 



= In the lower chalk-rubble silting in Cutting IX. there were occasional 

 seams of mixed silting (fine chalk with some mould) which was much com- 

 pressed and difficult to break up. There were more narrow seams of mould in 

 the chalk-rubble m this cutting than in the others previously excavated 



