Pinon Flat Obs. Middle Cretaceous granodiorite, decomposed at surface.
Sensors are on floor of buried shallow vault accessible by hatch door at surface.
Station Instrumentation 1. 19 Sep 1997 to Present 2. Oct 1995 to 18 Sep 1997 3. 10 Jan 1995 to 24 Oct 1995 4. 18 Aug 1994 to 18 Jan 1995 5.