Coring operations in the west basin of Clear Lake produced a regional Quaternary reference section to augment and extend a previous study of cores from Clear Lake. This report concerns 165.8—m—long core CL-80-2, which was continuously cored in 8.0 m of water and has a 65.0 percent recovery. The sedinents in core CL-80-2 are composed primarily of clayey and silty sapropelic mud that is similar to those presently being deposited in the lake. The core ended in coarse CO2—charged sand at 165.8 m. The age of sediment at the bottom of the core is inferred to be approximately 175,000 years.