Geochemical well logs were obtained in sediment at Sites 800, 801, and 802 of Ocean Drilling Program Leg 129. Corrections have been applied to the logs to account for variations in hole size, drilling-fluid composition, and drill-pipe attenuation. Oxide and calcium carbonate weight percentages have been calculated from the processed logs and are compared with the available measurements of core. Log-derived CaCO 3 measurements correlate well with shipboard CaCO 3 core measurements from Holes 800A and 802A. Log measurements are compared with X-ray fluorescence measurements from Holes 800A and 801B. Because of selective sampling from silica-rich beds, discrepancies between log and core data occur. The silica logs show values higher overall than those of the core measurements; the aluminum logs show values lower overall.