Young basalt lava flow delineation ( in contrast to detailed mapping of surface features) must be one of the easiest of mapping tasks: even a coarsely-textured image or DEM might serve the purpose Surface features of interest include tumuli, side-curtains , stony rises. For long flows, particular interest attaches to identifying lava channels that until roof collapse, were once part of the network of lava tubes to responsible for delivering molten lava to the flow front. The trace of hidden lava tube segments still retaining their rooves is indicated by the linearity of the interconnecting channel segments.
Except for a tephra mantle near the source fissure ( now occupied by Lake Surprise and a line of cinder cones, including Mt Eccles) the Tyrendarra lava flow in western Victoria, Australia, (approximately 40 000 years old ) is without continuous soil cover, and so many of the lave-flow surface features are still identifiable, although hard to map in the field because the terrain is famously inaccessible. Model-based ( 20m, 15m 10m and 7m DEMs) feature extraction techniques were deployed in order to identify any linearity of relevance to elucidating the nature of parts of the lava tube network that was near the surface. The closer to the source fissure, the higher the terrain and that more pronounced was the linearity of the channel-type features , suggesting that the source-end of the network was replaced many times by burial during high discharge episodes.