Could a seismic survey recognize the different lithologies of the Creede caldera in Colorado? To address this question, petrography and seismic properties of 46 tuff samples were analyzed with linear discriminant analysis and nonhierarchical clustering techniques. Results show that the lithological units mapped in the area can be characterized with petrographical variables (thin section point-count) but not recognized with seismic velocity, bulk density, and porosity variables. Seismic data are equally ineffective at recognizing samples that share common mineralogy across units. However, seismic data can recognize groups of samples that share similar porosity. We conclude that the study of variations in the porosity is the only feasible purpose of a seismic survey in an area similar to the one where our samples came from. Because of expected variations in porosity within cooling units of ash flow deposits, it may be relevant to run a seismic survey in the northern mining district of Creede to map the cooling history of the volcanic pile. ¿1991 American Geophysical Union