DIATOM-BASED INTERPRETATION OF SEDIMENT BANDING IN AN URBANIZED LAKE

Sediment stratigraphy and diatom succession were studied in an 80.5-cm core taken from the deepest part of Third Sister Lake, a small kettle hole in a recently urbanized landscape of southeastern Michigan. Alte rnating light clay and dark organic bands documented sporadic inputs o f clay from outside the basin during rain events, rather than annual l aminations. Urban construction activity also disrupted the inflow stre am bed and facilitated transport of clay into the lake to generate non -rhythmic banding in the lake's deep hole. Diatom analysis revealed dr amatic changes in predominant taxa with sediment depth verifying the n on-annual nature of the sediment bands. Observation of halophilic diat om taxa also documented effects of human activity such as road salting on this small, urban lake.