New Chirp and Vibracore data collected from the Kirby Hills Fault Zone in the Sacramento River reveal extensive deformation associated with the fault. Deformation of the river floor, in particular, is indicative of recent activity on the fault. The Kirby Hills Fault is a reactivated right lateral strike-slip fault that is synthetic to the San Andreas and Hayward faults nearby. This fault cuts through the Sacramento- San Joaquin Delta (Delta), which is an important part of California’s freshwater system, a unique habitat that supports a variety of plant and animal species and is also home to many human communities. Since this fault presents a great risk to the people and species inhabiting the area, we aim to constrain the rupture history of the fault. Sediment cores collected along the fault zone provide age constraints on deformation through radiocarbon dating and geologic correlation. The work presented here adds to the overall project by correlating geologic units in the sediment cores based on lithologic characteristics and clay geochemistry. These results will ultimately give us a better understanding of the deformational history of the Kirby Hills Fault, which in turn will support more accurate seismic hazards assessments for the region and better inform Delta stakeholders.