Subway Cave
Map SatelliteSometime less than 2,000 years ago a series of vents along a fissure trending northerly from near Old Station gave rise to the Hat Creek lava flow. The flow is pahoehoe with the typical undulating surface, partially ropy, and with many tumuli. A slump scarp some 5 meters (15 feet) high, at the eastern edge, at the foot of the Hat Creek fault scarp, was caused by the lowering of the central portion of the flow when the lava drained down the valley and shrank as it cooled and lost gas.
Subway Cave, one of a number in the flow, was a part of the main feeding tube of the flow. It was formed by the lava draining out of the tube at the close of the eruption. The cave has a flat floor, the congealed surface of the last of the fluid lava to drain out, which in places shows the clinkery surface characteristic of aa. The cave extends for some 700 meters (2,300 feet) and reaches a 15-meter (50-foot) diameter and 5-meter (16-foot) height. The entrance was formed by the collapse of a portion of the roof of the tube.
The rare herb Agastache parvifolia is found growing in the area.
Integrity: There is a campsite as well as a picnic area in the vicinity and a walkway has been built to facilitate entry.
Use: Research, educational, observational.
Ref: Anderson, C. A. 1940. Hat Creek Lava Flow (California). Am. Jour. Sci. Vol. 238 (7), pp. 477-492.
September 1975
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman