Wolf Island is the southerly island on the lineament. The volcano that formed Wolf Island is now extinct with last eruptions believed to have been 900,000–1,600,000 years ago, meaning the last eruptions occurred before the last eruptions on Darwin Island. The volcanic history of Wolf is complex, with at least two major eruptive phases. The southern area of the island is formed from flat basalt layers from two eruptive phases, the second of which formed a caldera that has now eroded. The lavas formed have been plagioclase ultraphyric basalts with large 4 cm crystals. This chemical makeup is similar to those found in lavas from the northern Galápagos Islands. The extent of the ultraphyric flows make up an unusually large percentage of the volume. There is large variation in the composition of the lavas between eruptive phases, with later flows being depleted.
