The first part of Chiliques to form was a block lava field, which still crops out northeast of the main volcano to a distance of . Lava flows with lengths of up to then constructed the stratovolcano proper and were later buried by shorter (up to ) lava flows that cover a surface of around the summit crater. The Cerro Overo maar northeast of Chiliques is occasionally considered the last phase of Chiliques's activity, and the two have erupted rocks with similar chemical composition. There is no evidence for historical activity.