# Relationship history for MSHA mine 1509989

Current hierarchy: **Treadway Shirley F → Brushy Fork Coal Company Inc → Surface**

- 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:** Brushy Fork Coal Company Inc → Surface; 1976-09-30 to 1976-12-07; source msha-controller-operator-history
- **controller_controls_mine:** Gilliam Berto → Surface; 1976-09-30 to 1982-05-06; source msha-controller-operator-history
- **controller_controls_operator:** Gilliam Berto → Brushy Fork Coal Company Inc; 1976-09-30 to 1976-12-07; source msha-controller-operator-history
- **operator_operates_mine:** Brushy Fork Coal Company Inc → Surface; 1976-12-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Treadway Shirley F → Surface; 1976-12-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Treadway Shirley F → Brushy Fork Coal Company Inc; 1976-12-08 to current/open; source msha-controller-operator-history