Bedrock velocities obtained from the inversion of first-break picks of multichannel seismic reflection data have been used to aid the interpretation of shallow reflectors. The trade-off between resolution and stability of inversion results has been examined. Models have been optimized by minimizing the variability of static corrections, and a Monte Carlo method has been used to estimate their precision. A velocity of 4.6¿0.4 km/s for the Leech River Complex (LRC) compares with velocities of 5.9¿0.6 and 5.8¿0.3 km/s for the neighboring geological units. Velocity contrasts associated with the change in lithologies may therefore be a contributing factor for generating reflections from the faults that bound the LRC. Velocities of 5.5¿0.4 and 4.6¿0.6 km/s on either side of the San Juan fault suggest that an event identified on several shot gathers may be a reflection from a steeply dipping fault. ¿American Geophysical Union 1987