PLATE I 
A. —Concrete tile on left laid in deep peat on University Marsh in 1918. Taken 
up in 1919. The tile to the right is new. 
B. —Concrete tile at left laid in peat 3^feet deep underlain by marl in University 
Marsh in 1914. .Taken up in 1919. The tile to the right is new. 
