Rgd. Davidsonarnott et Hec. Reid, SEDIMENTARY PROCESSES AND THE EVOLUTION OF THE DISTAL BAYSIDE OF LONG-POINT, LAKE ERIE, Canadian journal of earth sciences, 31(9), 1994, pp. 1461-1473
Long Point spit, on the north shore of lake Erie, is >40 km long and p
resently building into water that is >40 m deep. Annual sediment suppl
y to the spit is estimated to be 1.0 x 10(6) m(3).a(-1) and is derived
from the erosion of cohesive bluffs along more than 90 km of shorelin
e to the west. The shoreline of the distal bayside consists of narrow
barriers that connect the ends of dune ridges and enclose interdune po
nds and swales. Unlike most barrier spits, the distal end shows little
evidence of the formation of dune recurves, and the shoreline of the
bayside, rather than fronting a protected bay, is exposed to waves gen
erated by northeast winds blowing over a fetch > 100 km. Results of wa
ve refraction analysis indicate that because of the great depth of wat
er at the tip, there is almost no refraction of the dominant westerly
and southwesterly waves around the distal end, thus inhibiting the for
mation of recurves. Net sediment transport on the distal bayside is to
wards the distal end of the spit. The result is the development of a n
arrow spit platform extending the spit directly into the deepest part
of Lake Erie. All sediment reaching the distal end along the exposed s
outh shore is transported onto this platform and none reaches the dist
al bayside. The negative sediment budget on the distal bayside results
in transgression of the shoreline through truncation of the dune ridg
es, and overwash and breaching of the small barriers. Historical aeria
l photographs show that most of the overwash and breaching occurs duri
ng periods of long-term high lake levels, with the barriers being rebu
ilt landward of their former position during the following periods of
lower lake levels. Progradation of the south shore at the distal end i
s thus partly counterbalanced by the transgression of the bayside.