[1] They separate the San Jose neighborhoods of Almaden Valley to the west and Santa Teresa to the east.

Notable bodies of water include Santa Teresa Creek, which runs west down through the southern portion of the hills.

[2] Arroyo Calero then joins Alamitos Creek, which flows through Almaden Lake at the western end of the Santa Teresa Hills, exiting eventually to the Guadalupe River and then to the San Francisco Bay at Alviso.

[6] Like New Almaden, the Santa Teresa Hills contain “hilos,” or small tension fractures in silicate-carbonate rock containing veins of dolomite, quartz, and cinnabar, though in much lower quantity.

Serpentine soils are incredibly poor in essential plant nutrients like nitrogen and have high concentrations of heavy metals.

As such, the serpentine composition found in the Santa Teresa Hills provides an essential habitat for native plants that can tolerate these conditions from competition with non-native grasses.

The Santa Teresa Hills are a critical habitat for the threatened Bay checkerspot butterfly, whose primary host plant is the dwarf plantain.