Video: Undara lava tubes, Queensland
UNDARA’S VOLCANIC RIM stands a paltry 20m above the surrounding plains. However, in volcanism, elevation is not everything. Starting 190,000 years ago, Undara erupted, not with a bang but a long, seething gush of lava.
At times the rate of flow approached 1000 cu.m/second. As it moved on, the lava fabricated its own insulated pipeline. By the time Undara was a spent force its farthest run had travelled 160km.
From the air this course is legible today as a broken line of dense vegetation extending across sparse woodlands. These pockets of vine thicket sprout in moist depressions created by the collapse of sections of the lava tube’s roof.
Where the lid remains intact, long stretches of hollow lava tube survive. Many resemble abandoned train tunnels. Others form bridge-like archways interspersed with scree slopes and lush green courtyards.
Find out more in issue 126 (May/June) of Australian Geographic