# Relationship history for MSHA mine 4404249

Current hierarchy: **Potter Sanford → Solid Rock Coal Company Inc → No 1 Strip**

- 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:** Solid Rock Coal Company Inc → No 1 Strip; 1975-12-23 to 1976-07-20; source msha-controller-operator-history
- **controller_controls_mine:** Hay Webster C → No 1 Strip; 1975-12-23 to 1976-07-20; source msha-controller-operator-history
- **controller_controls_operator:** Hay Webster C → Solid Rock Coal Company Inc; 1975-12-23 to 1976-07-20; source msha-controller-operator-history
- **operator_operates_mine:** Solid Rock Coal Company Inc → No 1 Strip; 1976-07-21 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Potter Sanford → No 1 Strip; 1976-07-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Potter Sanford → Solid Rock Coal Company Inc; 1976-07-21 to current/open; source msha-controller-operator-history