Table 4. Mean posterior probability proportions of geochemical source contributions to observed variation in Chaco timber.

	Spruce	Fir	Ponderosa
Chuska Mountains	0.121	0.153	0.145
Chaco Watershed	0.125	0.159	0.145
Aztec Soil	0.100	0.126	0.143
San Mateo Mountains	0.475	0.319	0.168
San Pedro Mountains	0.021	0.030	0.063
La Plata Mountains	0.078	0.108	0.135
Hosta Butte	0.056	0.072	0.124
Cuba Mesa	0.025	0.033	0.076

For most potential timber geochemical sources, mean posterior proportion probabilities show little difference from prior probabilities. This indicates a high degree of uncertainty when attempting to use strontium to source timber samples. Only the San Mateo source emerges as a higher probability source for spruce (0.475) and fir (0.319).