LATE HOLOCENE LAKE-LEVEL AND LAKE DEVELOPMENT SIGNALS IN LOWER HERRING LAKE, MICHIGAN

Paleolimnological investigations of a marginal lake in the Lake Michig an basin revealed signals of long-term lake-level changes primarily co ntrolled by climatic forces. Multiple analyses identified concurrent s ignals in sediment chemistry, grain size, and the microfossil record. Coarse-grained sediments, benthic diatoms, and nutrient response speci es increased as lake levels rose or fell. Finer sediments and higher p ercentages of taxa associated with stable thermocline conditions occur red during high-lake periods. Sedimentary evidence revealed correspond ing strong high-lake signals c. 2500-2200, 1800-1500, 1170-730, and 50 0-280 BP. Low-lake periods occurred c. 1500-1170 and 700-500 B.P. An a dditional signal of lake-level decline was apparent beginning c. 280 B P but was interrupted by anthropogenic effects. Evidence of extreme lo w-lake levels (c. 1400-1300 BP), and signals for a medieval warming pe riod (1030-910 BP) and the Maunder minimum (370-325 BP) indicate occur rence of short-lived dry climatic conditions.