Geologic map of Johnny Lyon Hills is based on the published map by:

Harald Drewes, 1980

USGS

Units depicted in geologic map as described by Drewes:

Tc

Tv

Tva

Tlc                               cloudburst equivalent in J.L.H.

Kgb                             lower K balsal bisbee glance conglomerate.

Cs                                bolsa and abrigo