Between 25 million and 10 million years ago, two volcanoes erupted molten rock that was high in iron and magnesium and low in silica – basaltic lava. These cooled lava flows weathered and eroded over millions of years to form the Auckland Islands. Beneath the basalt is coarse-grained biotite granite base rock, which is up to 100 million years old. This rock is part of a granite belt extending from Stewart Island along the western margin of the Campbell Plateau.
How does the volcanic formation of the Auckland Islands impact the plant life?
Learn more about volcanic rocks.
Image acknowledgement: Sir Peter Blake Trust