# Relationship history for MSHA mine 1516121

Current hierarchy: **Zeigler Coal Holding Company → Clark Elkhorn Coal Company → Ratliff Mine No 110**

- 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:** Ratliff Elkhorn Coal Company → Ratliff Mine No 110; 1987-07-01 to 1992-11-22; source msha-controller-operator-history
- **controller_controls_mine:** Shell Oil Company → Ratliff Mine No 110; 1987-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Shell Oil Company → Ratliff Elkhorn Coal Company; 1987-07-01 to 1992-11-22; source msha-controller-operator-history
- **operator_operates_mine:** Clark Elkhorn Coal Company → Ratliff Mine No 110; 1992-11-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Zeigler Coal Holding Company → Ratliff Mine No 110; 1992-11-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zeigler Coal Holding Company → Clark Elkhorn Coal Company; 1992-11-23 to current/open; source msha-controller-operator-history