Relation to the civil origin
Valles Marineris's local civil time is derived from the Arabia Terra reference (MCT) with a −06:00 offset. This is not an independent standard — it is a regional display derived from MCT.
Function assignment — evidence status
Scientific Basis
Valles Marineris sits at low elevation, giving roughly double the average atmospheric pressure (~1.2 kPa) and canyon-wall lateral shielding that measurably reduces cosmic radiation exposure — both documented in published Mars-settlement research. Nearby water ice has also been confirmed. This is the strongest evidence-based case of the three regional function proposals.
References: Guo et al. radiation research; KTH Candor Chasma habitat study — see /research.