The Eagle Lake volcanic field occupies the junction of the Cascades, Sierra Nevada, and Basin and Range geologic provinces and consists of 15 cinder cones and basaltic lava flow vents within a larger Quaternary basaltic field. The vents are aligned along faults defining the Eagle Lake volcano-tectonic depression, and are the southernmost example of late Quaternary back-arc spreading in the northwestern Great Basin.
The three youngest volcanic lava flows at Eagle Lake yielded ages of 130.0±5.1, 127.5±3.2 and 123.6±18.7 ka, and are statistically indistinguishable. Paleomagnetic results demonstrate that two of the lava flows are very closely spaced in time, whereas the third is different by centuries to at most a few millennia. These results indicate that the basalt lava flows at Eagle Lake are not Holocene in age, and were erupted during an episode of volcanism at about 130–125 ka that is unlikely to have spanned more than a few thousand years. Thus, the short-term potential for subsequent volcanism at Eagle Lake is considered low.