10 000 yr record of extreme hydrologic events

Well-dated lacustrine sediments provide a hydrologic record indicating that the frequency and magnitude of runoff events, and by inference, storms, ha ve varied over the past 10 k.y. in northern New England, We used five sedim ent cores and radiocarbon dating to develop a chronology of Holocene hydrol ogic events for the Ritterbush Pond basin, northern Vermont. Chemical and p hysical analyses allow us to identify 52 distinct layers of predominately i norganic sediment that represent terrestrially derived material delivered t o the pond by runoff events. The thickness of some layers suggests hydrolog ic events at least equal in size to, and probably much larger than, any sto rm or flood recorded during nearly 300 yr of written regional history. Laye r thickness and frequency and, by analogy, storm size and recurrence, chang e through the Holocene. The Largest events occurred 2620, 6840, and 9440 ca librated C-14 years before present (cal C-14 yr B.P.). The most frequent hy drologic events occurred in three periods: 1750 to 2620, 6330 to 6840 and > 8600 cat yr B.P. The recurrence interval of layer deposition during stormy periods averages 130+/-100 cat yr, whereas the recurrence interval during l ess stormy periods is longer, 270+/-170 cal yr. The Ritterbush Pond event r ecord illustrates the potential of inorganic lacustrine sediment to serve a s a proxy record for estimating paleoflood frequency and deciphering climat e change.