Smn. Amin et Rgd. Davidsonarnott, TOE EROSION OF GLACIAL TILL BLUFFS - LAKE ERIE SOUTH SHORE, Canadian journal of earth sciences, 32(7), 1995, pp. 829-837
Toe erosion and rates of recession of the toe were measured at four si
tes along a 3.5 km long stretch of shoreline on the south shore of Lak
e Erie from April to December 1986. The shoreline consists of bluffs r
anging from 5 to 12 m in height and developed in overconsolidated till
. Toe erosion was measured at peg lines consisting of pins driven hori
zontally into the face of the bluff at 0.25 m intervals to a height of
1.75 m above the beach, and steel rods driven vertically into the bea
ch with a spacing of 1.5 m. At each site three lines were established
and monitored at 1-2 week intervals. Because of record high lake level
s, beaches in front of the bluffs were generally <5 m wide, and some e
rosion was measured on all but three occasions. Recession of the toe d
uring any measurement period was generally 2-6 cm, with the maximum re
corded being about 12 cm. Wave action during high-magnitude storms res
ulted in erosion occurring much higher up the bluff face than for low-
magnitude events, but the actual recession of the toe was not substant
ially greater. A multiple regression model shows that there is a signi
ficant relationship between toe recession and several variables that i
ndirectly control wave energy at the bluff toe. However, factors such
as beach width and thickness of beach sediment did not have a signific
ant influence on recession rates in this study, likely because the hig
h lake levels resulted in very narrow beaches at all four sites throug
hout the study period.