-1 Paleolimnological investigations of anthropogenic environmental change in Lake Tanganyika: II. Geochronologies and mass sedimentation rates based on 14 C and 210 Pb data Brent A. McKee 1, *, Andrew S. Cohen 2 , David L. Dettman 2 , Manuel R. Palacios-Fest 3 , Simone R. Alin 4 and Gerard Ntungumburanye 5 1 Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118, USA; 2 Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA; 3 Terra Nostra, Tucson, AZ 85741, USA; 4 School of Oceanography, University of Washington, Seattle, WA 98195, USA; 5 Institut Geographique du Burundi, Gitega, Burundi; *Author for correspondence (e-mail: bmckee@tulane.edu) Received 10 July 2004; accepted in revised form 15 January 2005 Key words: Deforestation, East Africa, Lake Tanganyika, Late Holocene, Mass accumulation rates, Soil erosion Abstract We established sediment geochronologies for cores from eight deltaic areas in Lake Tanganyika (the Lubulungu, Kabesi, Halembe, Malagarasi, Nyasanga/Kahama, Mwamgongo, Nyamusenyi, and Karonge/ Kirasa River deltas), recording a range of watershed disturbance histories from the eastern margin of this African rift valley lake. Cores from currently disturbed sites on the central Tanzanian coast display remarkably uniform and low rates of sediment accumulation from the 18th century until the early 1960s, when a synchronous and dramatic rise in rates occurs. Through this same time interval sedimentation rates offshore from undisturbed Tanzanian watersheds either remain unchanged or decline. Further north, at disturbed sites along the northern Tanzania and Burundi coasts, the pattern of sedimentation rate increase is more complex. Although a mid-late 20th century increase is also evident in these sites, indications of earlier periods of increasing sediment erosion, dating from the mid-late 19th century, are also evident. Synchronous changes in sediment accumulation rates dating from the early 1960s may be the result of exceptionally wet years triggering an increase in the discharge of previously eroded and unconsolidated alluvium and stream/beach terrace deposits, previously accumulated in the deltas and stream valleys of impacted watersheds. Sedimentation rate impacts of deforestation on lake ecosystems are likely modulated by short-term climatic forcing events, which can impact the specific timing and location of sediment discharge to lakes. Introduction Accurate assessment of changes in lacustrine sedi- mentation rates is a critical component of any paleolimnologic study attempting to document patterns and timing of anthropogenically-induced erosion. At Lake Tanganyika, Africa, as in many parts of the world, considerable agronomic, re- mote sensing, and anecdotal information exists suggesting that human-induced deforestation accelerated during the 20th century, and that this deforestation is likely to have generated increased Journal of Paleolimnology (2005) 34: 19–29 Ó Springer 2005 DOI 10.1007/s10933-005-2395-3