Debris-flow deposits and woody vegetation adjacent to and growing within the channels of Whitney, Bolam, Mud, Ash, and Panther creeks provide a 300-year record of debris-flow frequency at Mount Shasta Dendrochronologic (tree-ring) dating methods for the debris flows i~roved consistent with available documented rec- ords of debris flows Nine debris flows not reported in the historic record were documented and dated dendrochronologically The oldest tree-ring date for a mudflow was about 1670 Combined geomorphic and botanical evidence shows that debris flows are a common occurrence at Mount Shasta Debris flows trav- eling at least 2 km have occurred at the rate of about 8 3 per cen- tury Smaller debris flows occur substantially more frequently and usually do not proceed as far downslope as larger debris flows. Cy- clic scouring and filling by debris flows, in and adjacent to the stream channels, is suggested by dendrogeomorphic evidence and appears to be related to their magnitude and frequency Debris flows, small and large, may be the major surficial geomorphic agent in the vicinity of Mount Shasta, sculpturing the channels and developing large allu- vial fans