San Cristobal and Española are some of the oldest of the Galapagos Islands, as they sit on the southeastern end of the archipelago. The islands are of volcanic origin and formed due to the activity of what geologists call a “hotspot.” As the Nazca Plate slid to the southeast over the hotspot, new islands emerged. This means that the islands toward the northwest are the youngest, and the ones on the opposite end are the oldest.