VOLCORE, a global database of visible tephra layers sampled by ocean drilling

The VOLCORE (Volcanic Core Records) database is a collection of 34,696 visible tephra (volcanic ash and lithological or grain size variations) occurrences reported in the initial reports volumes of all of the Deep Sea Drilling Project (DSDP; 1966-1983), the Ocean Drilling Program (ODP; 1983-2003), the Integrated Ocean Drilling Program (IODP; 2003-2013) and the International Ocean Discovery Program (IODP; 2013-present) up to and including IODP Expedition 381. The combined international ocean drilling programmes (OD) have locations with global coverage. Cored tephra layers and tephra-bearing sediments span timescales from recent to ~150 million years in age. This database is a collection of information about reported visible tephra layers entirely or predominantly composed of volcanic ash. Data include the depth below sea floor, tephra thickness, location, and any reported comments. An approximate age was estimated for most (29,493) of the tephra layers using published age-depth models. The database can be used as a starting point for studies of tephrochronology, volcanology, geochemistry, studies of sediment transport and palaeoclimatology.