Rapid Dissolution of Avian Eggshells Buried by Mount St Helens Ash

Eggshells of ring-billed gulls buried by Mount St Helens ash at an eastern Washington colony were excavated one and seven years following the ashfall. These were compared to unburied eggshells. Physical dissolution of the eggshell had already begun during the first year of burial. After seven years most features of the eggshell had been lost, leaving a honeycombed mass. Physical dissolution was attributable to weak acids leaching through the ash.