The Mount Hamilton Cave (H-2, and nearby H-3 and H-30) is a complex system of moderately large bifurcating tubes at several levels (see map below; Ollier 1963, Webb et al, 1982). It is dominated by linear tubes rather than the broad low chambers typical of smaller subcrustal lava caves, which may indicate a more evolved style of larger subcrustal lava cave in which the original irregular chambers and small passages of subcrustal drainage caves in several stacked flows have combined and evolved into a more linear system of larger "feeder" tubes as lava flow continued through the conduit system on its way to the lava field below. This suggestion is supported by the presence of small 'proto-tubes', 20-60 cm in diameter, that are exposed by breakdown in the walls of the larger tubes in several parts of the cave.
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Map of Mt. Hamilton Cave, on the southern slopes of the lava shield. |
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Entrance to the main cave (3H-2) on the side of the mountain.. D050515.JPG |
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Typical large diameter passage. Smaller proto-tubes are exposed in the walls and roof of these passages. D050433.JPG |
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Small "proto-tube" exposed in the wall of a larger "evolved" tunnel. These may represent the initial stage with a network of small subcrustal tubes within the lava lobes. With time some tubes captured the main flow and enlarged while the others stagnated and in many cases solidified. This one may have remained connected to the larger tube and drained into it towards the end of the eruption. 10 cm scale bar. D050472.JPG |
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A pair of "Proto-tubes" in the ceiling of a larger tube. Stereopair - view cross-eyed. File: D050512.JPG and ..510 |
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Lava drips and a subsided section of the roof lining.. D050382.JPG |
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Anthodites on wall of tube. D050418.JPG |
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Mineral patterns. D050427.JPG |
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Water trickle pattern on an Actinomycete coating on a wall. D050507.JPG |
(c) KG. Grimes, 2006