To better understand what is going on in the recent volcanics of SW Victoria, an understanding of a couple of volcanic landforms is required:
Maar
a broad, low-relief volcanic crater that is caused predominantly by (highly explosive) phreatomagmatic eruptions (an explosion caused by rising magma coming into contact with ground or surface water). Maars range in size from 60 to 8,000 m across and from 10 to 200 m deepMost maars have low rims composed of a mixture of loose fragments of volcanic rocks and rocks torn from the walls of the vent. Maars typically fill with water to form a relatively shallow crater lake.
Scoria or Cinder Cone
a volcanic cone built almost entirely of loose volcanic fragments called scoria or cinders. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, e.g. fire fountaining, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone. Most cones have a bowl-shaped crater at the summit. Cinder cones rarely rise more than 300 to 750 m or so above their surroundings, and, being unconsolidated, tend to erode rapidly unless further eruptions occur.
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