Ta. Thompson et Sj. Baedke, BEACH-RIDGE DEVELOPMENT IN LAKE-MICHIGAN - SHORELINE BEHAVIOR IN RESPONSE TO QUASI-PERIODIC LAKE-LEVEL EVENTS, Marine geology, 129(1-2), 1995, pp. 163-174
Strandplains of arcuate beach ridges are common in coastal embayments
in parts of the Great Lakes. Similarities in beach-ridge development a
nd geomorphology are recognizable in many of the embayments in the Lak
e Michigan basin despite differences in size and shape, available sedi
ment type and supply, predepositional slope and topography, and hydrog
raphic regime between the embayments. These similarities are primarily
a product of three scales of quasiperiodic lake-level variation rangi
ng in time from 30 to 600 years and in water level change from 0.5 to
3.7 m. The interaction of these three lake-level variations can be rep
resented on a Curray (1964) diagram (rate of water level change versus
rate of sediment supply). The position of any shoreline on the diagra
m and the type of behavior the shoreline is experiencing is a product
of the interaction of the three variations. Two large strandplains of
late Holocene beach ridges occur at opposite ends of Lake Michigan (To
leston Beach and Thompson embayment). The two areas exhibit similar pa
tterns of beach-ridge development for the past 2600 calendar years. Th
at is, both areas form beach ridges about every 30 years. Groups of 4
to 6 beach ridges reflect a longer-term lake-level variation of about
150 years. Only during the largest variation of about 600 years in dur
ation do the two areas differ. The rise to the 1700 cal yr B.P. high c
aused the erosion of beach ridges back to 2800 cal yrs B.P. in norther
n Lake Michigan. In southern Lake Michigan, no erosion occurred during
this lake level high. Differences in shoreline development between th
e two areas are related to the rate of sediment supply to the shorelin
es. As the sediment sink for the southern half of Lake Michigan, the s
outhern strandplain received a greater sediment flux than the northern
strandplain during the latter part of the late Holocene and produced
a continuous record of beach-ridge development.