Holocene Alluvial Fills in the South Loup Valley, Nebraska

Four Holocene alluvial fills are present in Nebraska's South Loup River valley. Fill IV, the oldest and thickest, was deposited between 10,200 and 4800 14 C yr B.P.; Fill III has an age of about 3000 14 C yr B.P.; Fill II is younger than 2100 and older than 900 14 C yr B.P.; and Fill I is younger than 900 14 C yr B.P. Regional contemporaneity of valley alluviation in the eastcentral Great Plains suggests that climate has controlled long-term sediment storage in the South Loup River valley.