# Relationship history for MSHA mine 1508899

Current hierarchy: **B Ray  Thompson → Greenwood Land & Mining Company Inc → No 4 (Surface)**

- 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:** Greenwood Land & Mining Company Inc → No 4 (Surface); 1975-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** B Ray  Thompson → No 4 (Surface); 1975-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** B Ray  Thompson → Greenwood Land & Mining Company Inc; 1975-01-01 to current/open; source msha-controller-operator-history