A thick pile of andesitic lava flows with additional scoria and which crops out on the southern, southeastern and southwestern side of the Ampato volcano is the oldest volcanic stage of this volcano, with argon-argon dating yielding ages between 400,000 - 450,000 years before present. Above this formation, another pile of dacitic lava flows constructed the first Ampato edifice, which was about the same size as the present-day volcano. This pile (Moldepampa stage) is about thick in outcrops and was emplaced between 230,000 - 200,000 years before present.