# Relationship history for MSHA mine 2901073

Current hierarchy: **CRH PLC → Four Corners Materials → NM Wash Plant**

- 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:** Arco Materials Inc → NM Wash Plant; 1950-01-01 to 1990-05-17; source msha-controller-operator-history
- **controller_controls_mine:** Ronald W  Southard → NM Wash Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ronald W  Southard → Arco Materials Inc; 1950-01-01 to 1990-05-17; source msha-controller-operator-history
- **operator_operates_mine:** Arco Materials Inc → NM Wash Plant; 1990-05-18 to 1997-03-31; source msha-controller-operator-history
- **controller_controls_mine:** John J  Siegrist → NM Wash Plant; 1990-05-18 to 1997-03-31; source msha-controller-operator-history
- **controller_controls_operator:** John J  Siegrist → Arco Materials Inc; 1990-05-18 to 1997-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Four Corners Materials → NM Wash Plant; 1997-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → NM Wash Plant; 1998-01-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Four Corners Materials; 1998-01-05 to current/open; source msha-controller-operator-history