Another gravity anomaly occurs 1200 m from the west portal at the intersection of the tunnel and the surface trace of the Oatfield fault. A steeply dipping fault identified inside the tunnel at this same location has placed 15 Ma Columbia River basalt 20 m above 1 Ma Boring Lava. We believe the fault identified inside the tunnel at 1200 m from the west portal is a segment of the Oatfield fault and is the cause of the associated gravity anomaly. Stability of Borax Lake With Ansel Johnson, Michael Cummings and graduate student Sean Wilson. Borax lake is a hot spring located a few km from Fields in SE Oregon, in the Alvord Desert.
Borax Lake is a located atop a small mound.
The area around the hot spring has been armored with sinter and so now stands as a topographic high. Under the sinter is a diatomaceous material with very low remolded strength. Borax Lake contains a unique species of chub that is on the endangered species list. This gives the fish a wider range of water temperatures and helps keep the average temperature more stable. Increasing the water level has also increased some spring activity on the flanks of the mound.