Western Victorian volcanic research
Photographs and descriptions of the lava flows at Byaduk Caves and Mount Napier in Notebook 17, page 7.
The volcanic plains of Western Victoria were a rich hunting ground for Edmund Gill and continue to be so for other geologists and researchers. The plains extend from Melbourne to the South Australian border and there are about 400 volcanoes within the region, which have been erupting intermittently for five million years.6
One of these volcanoes is Mount Napier, which erupted about 36,000 years ago. The lava flow from Mount Napier ran down Harman's Valley to the west, and formed significant examples of tumuli along the way. Tumuli form when the surface of the lava flow becomes crusted; the pressure within the flow can then force its way through the surface, forming mounds. Lava can also form open caves (when the lava drains away from the crust) and lava tubes, which enable the lava to flow long distances.7
As the Mount Napier eruption is comparatively young, significant examples of geological formations created by the lava flow are easily seen in the Harman's Valley area. The tumuli along the flow are considered the best developed in Australia and are relatively uncommon in the rest of the world. Lava caves and tubes can be seen clearly at nearby Byaduk.8
Edmund Gill's notebooks include photos of these features, and diagrams and notes which describe the processes which took place thousands of years ago.
Information gathered by Gill and other researchers can help inform decision making when dealing with these landscapes and their remarkable geological features. Balancing usage, access and preservation in land management is becoming increasingly challenging in the modern era, as was demonstrated recently when part of Harman's Valley was ploughed.9