Off Baja California (Guadalupe Site) at a water depth of 11,706 ft, drilling penetrated about 560 ft of sediments before entering an olivine basalt flow; 8 sedimentary samples were obtained for the present study. One sample was obtained from the core taken off LaJolla, California, in a water depth of 3109 ft where drilling was to 1043 ft below the sea floor. Two samples for the present study are surface samples from the Guadalupe Site. A pycnometer was used to determine bulk densities of the samples. The sediments examined contain appreciable amounts of clay minerals which lose water from their structure at varying rates and amounts at different drying temperatures. Consequently, bulk densities of the mineral grains vary considerably with the temperature of drying. The densities increase as the temperature of drying is increased. The bulk specific gravity of mineral grains in Guadalupe Site samples varied between 2.75 and 2.47 g/cc; the average of all determinations at 105 degrees C. was 2.59 g/cc.