Ascraeus Mons Summit
This complex caldera is composed of several discrete
centers of collapse where the older collapse features are cross-cut by more recent
collapse events. The lowermost circular floor preserves the last lava flooding event
that followed the last major collapse. The southern wall of the caldera has at least
3 kilometers (1.9 miles) of vertical relief with an average slope of at least 26° (from
horizontal). The caldera complex truncates several lava flows, indicating that the
flows predate the collapse event and that their source areas have been destroyed by the
caldera formation.