Mount Sanford dikes (Pleistocene). Chiefly dikes of andesitic composition that have probably widely diverse ages; associated with main Sanford center, three subsidiary centers, and smaller satellitic vents. Not all dikes shown on map sheet were examined in the field; those that were visited and sampled are mostly gray, porphyritic two-pyroxene andesite and olivine andesite, mineralogically similar to host Sanford lava flows (Qsl). * * * Whole-rock K-Ar age of 0.78+/-0.08 Ma was determined on sample 74-ALe-63.
Geologic map of the Gulkana A-1 Quadrangle, south-central Alaska