# Relationship history for MSHA mine 3503603

Current hierarchy: **Trevor  Smith; William  Unterberger → Pacific Coast Rock LLC → Ekroth Quarry**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Pacific Coast Rock LLC → Ekroth Quarry; 2004-09-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** William  Unterberger et al → Ekroth Quarry; 2004-09-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William  Unterberger et al → Pacific Coast Rock LLC; 2004-09-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Trevor  Smith et al → Pacific Coast Rock LLC; 2004-09-23 to current/open; source msha-controller-operator-history