PLATE 3 
A. —Tile from University Marsh. From same line as in Plate iB, but taken up in 
fall of 1920. Note progressive disintegration in Plates i, A, i, B, and 3, A. 
B. —Concrete culvert in Gaynor Road, Grand Rapids, Wis. Built about 1910. 
Photographed September, 1920. Acid water from the cranberry marshes stands 
against the concrete at all times. 
