# Relationship history for MSHA mine 1505207

Current hierarchy: **Shell Oil Company → Ratliff Elkhorn Coal Company → Ratliff Elkhorn Tipple No 1**

- 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:** Ratliff Elkhorn Coal Company Inc → Ratliff Elkhorn Tipple No 1; 1950-01-01 to 1987-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Massey Energy Company → Ratliff Elkhorn Tipple No 1; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Massey Energy Company → Ratliff Elkhorn Coal Company Inc; 1950-01-01 to 1987-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Shell Oil Company → Ratliff Elkhorn Tipple No 1; 1987-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ratliff Elkhorn Coal Company → Ratliff Elkhorn Tipple No 1; 1987-07-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Shell Oil Company → Ratliff Elkhorn Coal Company; 1987-07-10 to current/open; source msha-controller-operator-history