# Relationship history for MSHA mine 4503497

Current hierarchy: **CRH PLC → American Rock Products Inc → Whitcomb 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 → Whitcomb Quarry; 1987-09-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Eucon Corporation → Whitcomb Quarry; 1998-02-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mainline Rock & Ballast Inc → Whitcomb Quarry; 2001-08-27 to 2009-06-21; source msha-controller-operator-history
- **controller_controls_operator:** Eucon Corporation → Mainline Rock & Ballast Inc; 2001-08-27 to 2009-06-21; source msha-controller-operator-history
- **controller_controls_mine:** Eucon Corporation → Whitcomb Quarry; 2001-09-10 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** American Rock Products Inc → Whitcomb Quarry; 2009-06-22 to 2018-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Eucon Corporation → American Rock Products Inc; 2009-06-22 to 2018-03-31; source msha-controller-operator-history
- **operator_operates_mine:** American Rock Products Inc → Whitcomb Quarry; 2018-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → American Rock Products Inc; 2018-04-01 to current/open; source msha-controller-operator-history