Hayrick Butte is of late Pleistocene age. Like Hogg Rock, Hayrick Butte is an andesite lava dome with a flat top, suggesting that it is also a tuya, or a subglacial volcano. Both volcanic features have been eroded by glaciation, leaving glassy margins and jointing. Both Hayrick Butte and Hogg Rock produced porphyritic andesite lava with plagioclase and orthopyroxene and trace levels of phenocrysts with olivine. Hayrick Butte also served as a barrier for Hoodoo Butte during the Pleistocene glaciation, blocking the advancement of glacial ice from eroding Hoodoo's summit crater.