The data in this file represent measurements of the the depth, grain size characteristics and sedimentation rate for sediment cores collected from the floodplain of the Rio Beni in 2011, 2012, and 2013. The age of floodplain sediments was determined from measurements of the Pb-210 activity of floodplain sediments within the cores. The sample collection and laboratory techniques and data analysis procedures used to obtain these data are described in: Aalto, R & Nittrouer, C.A. (2012) Phil. Trans. Royal. Society., vol 370, p 2040-2074. This is an ascii text comma delimited file. Each row in the file represents a sediment core. The file contains 12 columns of data representing: column 1: The core name column 2: The latitude of the core location in digital degrees column 3: The longitude of the core location in digital degrees column 4: The year in which the core was collected column 5: The depth of the floodplain core (in cm) column 6: The age of the oldest sediment in the core (in years) column 7: The depth to the oldest sediment in the core (in cm) column 8: The estimated mean sedimentation rate for the core (in cm per year) column 9: The percentage of the core comprised of clay column 10: The percentage of the core comprised of silt column 11: The percentage of the core comprised of sand column 12: The mean density of sediment in the core (in g per cubic cm)