# Relationship history for MSHA mine 4105372

Current hierarchy: **Amrize South Central → Permian Basin Materials Aggregate → Buckhorn**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** W L Ross & Co LLC et al → Buckhorn; 2015-08-01 to 2026-02-17; source msha-controller-operator-history
- **operator_operates_mine:** Permian Basin Materials LLC → Buckhorn; 2018-06-20 to 2026-02-17; source msha-controller-operator-history
- **controller_controls_operator:** W L Ross & Co LLC et al → Permian Basin Materials LLC; 2018-06-20 to 2026-02-17; source msha-controller-operator-history
- **controller_controls_mine:** Amrize South Central → Buckhorn; 2026-02-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amrize South Central → Permian Basin Materials LLC; 2026-02-18 to 2026-02-17; source msha-controller-operator-history
- **operator_operates_mine:** Permian Basin Materials Aggregate → Buckhorn; 2026-02-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amrize South Central → Permian Basin Materials Aggregate; 2026-02-18 to current/open; source msha-controller-operator-history