Hayes Volcano - Physical Setting

Physical Setting

Hayes Volcano is an ice-shrouded, glacially scoured eruptive center of Quaternary age composed of pyroclastic deposits, volcanic breccia, and lava domes. Although the edifice of the volcano is largely covered by glacier ice, parts of small lava domes, dome debris, and pyroclastic deposits project through the ice at altitudes of 2,400 to 2,800 meters above sea level. The volcano is nestled within the Tordrillo Mountains, a rugged, glacier-clad mountain range, between the Alaska Range and Cook Inlet, that is composed primarily of older plutonic igneous rocks. Most of the area is in high relief (greater than 1,500 meters) and supports an extensive complex of glacier ice that covers most of the mountainous terrain. The volume of perennial snow and glacier ice on Hayes Volcano is not known but is comparable to the ice volume present on Mount Spurr volcano (to the south), which supports about 67 km³ of ice and perennial snow.

Unlike the other volcanoes in the Cook Inlet area, Hayes Volcano lacks a well-defined cone, and deposits from eruptions older than the 4,400-to-3,600-year-old eruption are not known. The volcano is unusual in this regard because all other volcanoes in the Cook Inlet area consist of relatively voluminous assemblages of volcanic rock and debris that formed over many tens of thousands of years.