# Relationship history for MSHA mine 3503968

Current hierarchy: **CRH PLC → American Rock Products → Grubbs 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** CRH PLC → Grubbs Quarry; 1987-09-18 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** American Rock Products → Grubbs Quarry; 2024-10-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → American Rock Products; 2024-10-30 to current/open; source msha-controller-operator-history