GLACIAL - INTERGLACIAL ENVIRONMENTAL CHANGE AS INFERRED FROM ORGANIC CONTENT AND CARBON ISOTOPE ANALYSIS OF PEAT, BREWSTER BOG, OHIO

Sediments from Brewster Bog, northeastern Ohio provide a detailed record of late Pleistocene and early Holocene environmental change. Organic material from a 9.5 m-long core was analyzed to evaluate changes in organic productivity and landscape stabilization after glaciation. Carbon isotope ratios of peat from the core were analyzed to investigate moisture changes over the last glacial – interglacial transition. The sediments record a classic deglacial climate sequence. The post-glacial Bølling-Allerød warming is indicated by an abrupt upcore increase in organic content ca. 12,740±100 ¹⁴C yr B.P. (AA53416). A subsequent sharp decrease in organic content is suggestive of the inception of a cool period and resembles a Younger Dryas signal, but is slightly older (11,380±50 ¹⁴C; Beta-172290) than the Younger Dryas interval recorded elsewhere in the region. The onset of Holocene warming after this interval is evident in an upcore change from low to very high organic content. Carbon isotopes from Sphagnum peat also suggest multiple dry periods during the early Holocene. The Brewster basin progressed through wetland phases in response to variations in climate. The carbon isotope data indicate that a transition from fen to bog occurred synchronous with the termination of the Younger Dryas. This localized environmental change is attributed to lower water levels induced by Younger Dryas aridity. Correlation with regional palynological and stratigraphic data suggests that the environmental changes recorded in Brewster Bog occurred in response to regional-scale climate variations.