# Relationship history for MSHA mine 4201076

Current hierarchy: **Warburton Inc → Warburton Sand & Gravel → American Fork 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

- **operator_operates_mine:** Warburton Sand & Gravel → American Fork Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Warburton Inc → American Fork Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Warburton Inc → Warburton Sand & Gravel; 1950-01-01 to current/open; source msha-controller-operator-history