14 
BULLETIN 1419, U. S. DEPARTMENT OF AGRICULTURE 
the bearing capacity of peat layers under concentrated loads. Figure 
4 is instructive in snowing the depth of penetration of a load and the 
compression and change in position of layers resulting from an OVer- 
flll PAVEMENT gH CLAY 
p^j COARSE GRAVEL $£j\ SAND 
m 
FINE GRAVEL 
PULPY «o MARLY 
PULPY PEAT 
MIXED PHASES OF 
SEDGE «° PULPY PEAT 
REED*™ PULPY 
REED PEAT 
SEDGE PEAT 
WOOD'T PEAT 
^~ 
Fig. 4.— Displacement of peat layers under heavy road beds. Compare with Plate 7. (Courtesy 
of Michigan State Highway Department) 
burden of fill used in the construction of highways. The areas under 
pressure yield gradually by plastic flow and may cause the sinking of a 
roadbed, as well as a lateral expansion and upheaval of adjacent 
peat layers. Engineering literature contains hardly a single descrip- 
