# Relationship history for MSHA mine 4102422

Current hierarchy: **Hanson PLC → Gifford-Hill & Company → Yelverton Pit**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Hanson PLC → Yelverton Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** D P Frost Construction Company Inc → Yelverton Pit; 1950-01-01 to 1986-10-23; source msha-controller-operator-history
- **controller_controls_mine:** D P  Frost → Yelverton Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** D P  Frost → D P Frost Construction Company Inc; 1950-01-01 to 1986-10-23; source msha-controller-operator-history
- **operator_operates_mine:** Gifford-Hill & Company → Yelverton Pit; 1986-10-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Gifford-Hill & Company; 1986-10-24 to current/open; source msha-controller-operator-history