# Relationship history for MSHA mine 4000524

Current hierarchy: **Massey Energy Company → Grundy Mining Company Inc → Mine No 21**

- 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:** Grundy Mining Company Inc → Mine No 21; 1950-01-01 to 1976-08-31; source msha-controller-operator-history
- **controller_controls_mine:** Tennessee Consolidated Coal Company Inc → Mine No 21; 1950-01-01 to 1976-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Tennessee Consolidated Coal Company Inc → Grundy Mining Company Inc; 1950-01-01 to 1976-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Grundy Mining Company Inc → Mine No 21; 1976-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Massey Energy Company → Mine No 21; 1976-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Massey Energy Company → Grundy Mining Company Inc; 1976-09-01 to current/open; source msha-controller-operator-history