# Relationship history for MSHA mine 2301928

Current hierarchy: **CRH PLC → Conco Quarries, Inc. A CRH Company → Conco Quarries-Marshfield**

- 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 → Conco Quarries-Marshfield; 1950-01-01 to 2018-06-20; source msha-controller-operator-history
- **operator_operates_mine:** Ash Grove Aggregates Inc → Conco Quarries-Marshfield; 1985-07-01 to 2020-06-29; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Ash Grove Aggregates Inc; 1985-07-01 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Conco Quarries-Marshfield; 2018-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Ash Grove Aggregates Inc; 2018-06-21 to 2020-06-29; source msha-controller-operator-history
- **operator_operates_mine:** Conco Quarries, Inc. A CRH Company → Conco Quarries-Marshfield; 2020-06-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Conco Quarries, Inc. A CRH Company; 2020-06-30 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Conco Quarries, Inc. A CRH Company; 2020-06-30 to current/open; source msha-controller-operator-history