# Relationship history for MSHA mine 1600907

Current hierarchy: **Richardson R D → D & J Sand & Gravel → Browning 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** H & M Dirt Company → Browning Pit; 1950-01-01 to 1979-10-02; source msha-controller-operator-history
- **controller_controls_mine:** Mathis George & Felton Hart → Browning Pit; 1950-01-01 to 1979-10-02; source msha-controller-operator-history
- **controller_controls_operator:** Mathis George & Felton Hart → H & M Dirt Company; 1950-01-01 to 1979-10-02; source msha-controller-operator-history
- **operator_operates_mine:** D & J Sand & Gravel → Browning Pit; 1979-10-03 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Richardson R D → Browning Pit; 1979-10-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richardson R D → D & J Sand & Gravel; 1979-10-03 to current/open; source msha-controller-operator-history