Stratigraphy of the Sixteen Mile Creek lagoon, and its implications for Lake Ontario water levels

Abstract

The sequence of units (from the base up) in the Sixteen Mile Creek lagoon (Lake Ontario) mimics the longitudinal sequence of surficial environments: pink silt-overbank (flood plain -dry marsh); bottom sand-stream channel and beach; orange silt-marsh; gyttja-wet marsh and very shallow (deltaic) lagoon; and brown and grey clay-open-water lagoon. This entire sequence accumulated over the last 4200 years under slowly deepening, transgressive conditions caused by the isostatic rise of the lake outlet. Land clearing by European settlers dramatically increased the supply of clastic sediment and terminated the deposition of the organic-rich silty clays (gyttja) that make up most of the lagoon fill.Because the gyttja and beach sand are interpreted to have accumulated in water depths of less than 0.5 m, the elevationtime plot of 14C dates from these units can be used to reconstruct a very closely constrained lake-level curve. The data indicate that water levels have risen at an average rate of 0.25 cmla over the last 3300 years as a result of differential, isostatic rebound. Superimposed on this trend are water-level oscillations with amplitudes on the order of 1 m and periods of several hundred years. These oscillations are synchronous and in phase with water-level fluctuations in Lake Michigan, and with a variety of other climatic variations in North America and Europe. We propose, therefore, that the water-level oscillations are a result of long-term, climatically produced variations in precipitation in the Great Lakes drainage basin.La sCquence des unites (de bas en haut) dans la lagune de Sixteen Mile Creek (lac Ontario) correspond ti une sCquence longitudinale dCvelopp6e en surface : limon rose-alluvion (plaine de d6bordement -marais sec); sable de couches de fond-chenal de rivibre et plage; limon orangC-marais; gyttja-marais humide et lagune peu profonde (deltaique); argile brune et grise-lagune ouverte. I1 a fallu les derniers 4200 ans pour accumuler cette s6quence en entier, dans des conditions de transgression et de d6pression lente, dues ti la remontee isostatique de I'orifice du lac. Le dCfrichage des terres par les colons europCens a dramatiquement augment6 l'apport en sediment clastique et s'est termin6 par l'accumulation d'argiles riches en matibre organique (gyttja) remplissant la majeure partie de la lagune.Vu que les sCdiments de type gyttja et les sables de plage ont vraisemblablement sediment6 dans moins de 0,5 m d'eau, la courbe altitude-temps des dates 14C de ces unitCs peut servir pour reconstruire une courbe des variations bien dCfinies des niveaux du lac. Les donnees rCvblent que le rebondissement isostatique differentiel est responsable de 1'61Cvation des niveaux de l'eau avec un taux moyen de 0,25 cmla durant les derniers 3300 ans. En plus, il y a eu superposition d'oscillations du niveau de l'eau de l'ordre d'un mbtre avec amplitudes de plusieurs s2cles. Ces oscillations correspondent dans le temps et en phase avec les fluctuations du niveau de l'eau du lac Michigan, et avec diverses autres vari...

Late Holocene lake-level and lake development signals in Lower Herring Lake, Michigan

“…This shift from a previously warm-dry climate should produce a distinctive increase in water level. Fraser et al (1990) found evidence of a rapid rise in Lake Michigan levels (c. 1165 BP) and similar high levels have been discovered in Lake Ontario between 1200 and 950 BP (Flint et al, 1988).…”

“…This period of decline agrees with the first low-water signal found in Lower Herring Lake at 350-330 cm (c. 3900-3570 BP) and the second high stage corresponds to the subsequent Algoma phase. A concurrent rise during this time (c. 3300-3100 BP) has also been reported from the sediment record of Lake Ontario (Flint et al, 1988;McCarthy & McAndrews, 1988;Dalrymple & Carey, 1990). The second lowwater signal at 305-285 cm (c. 3150-2900 BP) corresponds to the post-Algoma low of Larsen (1985a) and Fraser et al (1990).…”

“…Cool-dry conditions existed in the region between 700 and 500 BP (Bernabo, 1981;Gajewski, 1988) and correspond closely to the low-lake stage identified in Lower Herring Lake. Reconstructions for southern Lake Michigan (Larsen, 1985a, b) also indicate similar timing of a low-water period and lower levels were also present in Lake Ontario from 950 to 400 BP (Flint et aL, 1988).…”

Floodplain formation processes and archaeological implications at the Grand Banks site, lower Grand River, southern, Ontario

“…Coakley and and Anderson and Lewis (1985) have argued for it consistently in constructing Lake Ontario and Lake Erie Holocene lake levels. In contrast, Flint et al (1988) and Weninger and McAndrews (1989) found little evidence for it in flood-ponds near basin outlets at the west end of Lake Ontario. The need to better define water levels in the middle Holocene represents an area in need of further research.…”

Pre-settlement Snail Fauna on the Sandbanks Baymouth Bar, Lake Ontario, Compared with Nearby Contemporary Faunas

“…Fluc tuation occurred in the early postglacial time (Jackson et al 2000), and, much later (3000-2100 years BP), there were also periods of rapid rise in water level related to episodes of relatively cool, wet climate (McCarthy and McAndrews 1988). Also superimposed on the general rising trend, Flint et al (1988) reported oscillations over the past 3300 years, with an amplitude in the order of 1 m over several hundred years. These oscillations have also been related to longer-term climate changes (McCarthy 1986).…”