# Relationship history for MSHA mine 4607008

Current hierarchy: **Van Gilder Ernest J → W C Tonkery Coal Company Inc → Sweeps Mine 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** William C Tonkery Coal → Sweeps Mine No 1; 1985-09-01 to 1987-02-11; source msha-controller-operator-history
- **controller_controls_mine:** Tonkery William C → Sweeps Mine No 1; 1985-09-01 to 1987-02-11; source msha-controller-operator-history
- **controller_controls_operator:** Tonkery William C → William C Tonkery Coal; 1985-09-01 to 1987-02-11; source msha-controller-operator-history
- **operator_operates_mine:** W C Tonkery Coal Company Inc → Sweeps Mine No 1; 1987-02-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Van Gilder Ernest J → Sweeps Mine No 1; 1987-02-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Van Gilder Ernest J → W C Tonkery Coal Company Inc; 1987-02-12 to current/open; source msha-controller-operator-history