# Relationship history for MSHA mine 3500556

Current hierarchy: **CRH PLC → Valley Concrete & Gravel Co. → Valley Concrete & Gravel Prtbl Crusher**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Valley Concrete & Gravel Company → Valley Concrete & Gravel Prtbl Crusher; 1950-01-01 to 2006-06-30; source msha-controller-operator-history
- **controller_controls_mine:** J C Compton Company → Valley Concrete & Gravel Prtbl Crusher; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** J C Compton Company → Valley Concrete & Gravel Company; 1950-01-01 to 2006-06-30; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Valley Concrete & Gravel Prtbl Crusher; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Valley Concrete & Gravel Co. → Valley Concrete & Gravel Prtbl Crusher; 2006-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Valley Concrete & Gravel Co.; 2006-07-01 to current/open; source msha-controller-operator-history