[1] The volcanic group consists predominantly of alkali basalts with minor hawaiites, benmoreites and mugearites.

They are interpreted to have been deposited by volcanic eruptions in an extensional back-arc setting after subduction had ceased along the western margin of the Antarctic Peninsula.

[1] However, volcanic rocks as young as only a few thousand years old may exist on James Ross Island.

[2] Rocks of the James Ross Island Volcanic Group comprise Surtseyan tuff cones and Strombolian cinder cones, as well as lava deltas and overlying subaerial lava flows.

[1] The dominating feature of the James Ross Island Volcanic Group is Mount Haddington, a massive shield volcano of Miocene-to-Pliocene age on James Ross Island.