# Relationship history for MSHA mine 2301778

Current hierarchy: **CRH PLC → Ash Grove Aggregates Inc → SHAMROCK AGGREGATES INC**

- 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:** Ash Grove Cement Company → SHAMROCK AGGREGATES INC; 1950-01-01 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → SHAMROCK AGGREGATES INC; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Corp → SHAMROCK AGGREGATES INC; 1979-10-01 to 1990-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Corp; 1979-10-01 to 1990-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Ash Grove Aggregates Inc → SHAMROCK AGGREGATES INC; 1990-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Ash Grove Aggregates Inc; 1990-10-01 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → SHAMROCK AGGREGATES INC; 2018-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Ash Grove Aggregates Inc; 2018-06-21 to current/open; source msha-controller-operator-history