Chap. IV. OF ANCIENT BUILDINGS. 225 



Measurements by Dr. H. Johnson of the thickness of 

 the vegetable mould over the roman ruins at 

 Wroxeter. 



Trenches dug in a field called " Old Works." 



Thickness 



of mould in 



inches. 



1. At a depth of 36 inches undisturbed sand was 



reached .. .. .. .. ..20 



2. At a depth of 33 inches concrete was reached 21 



3. „ „ 9 inches concrete was reached 9 



Trenches dug in a field called ''Shop 

 Leasows ;" this is the highest field within the 

 old walls, and slopes down from a sub-central 

 point on all sides at about an angle of 2°. 



Thickness 



of mould in 



inches. 



4. Summit of field, trench 45 inches deep .. 40 



5. Close to summit of field, trench 36 inches deep 26 



6. „ „ trench 28 inches deep 28 



7. Near summit of field, trench 36 inches deep 24 



8. „ „ trench at one end 39 

 inches deep ; the mould here graduated into 

 the underlying undisturbed sand, and its 

 thickness (24 inches) is somewhat arbitrary. 

 At the other end of the trench, a causeway 

 was encountered at a depth of only 7 inches, 

 and the mould was here only 7 inches thick 24 



9. Trench close to the last, 28 inches in depth . . 15 



10. Lower part of same field, trench 30 inches deep 15 



11. „ „ trench 31 inches deep 17 



12. „ „ trench 36 inches deep, 



at which depth undisturbed sand was reached 28 



