# Relationship history for MSHA mine 1515021

Current hierarchy: **Taylor Mike → Wormey Coal Company → Wormey Coal No 4**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Rick Coal Company → Wormey Coal No 4; 1983-09-20 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rick Coal Company → Wormey Coal No 4; 1984-12-01 to 1985-03-26; source msha-controller-operator-history
- **controller_controls_operator:** Rick Coal Company → Rick Coal Company; 1984-12-01 to 1985-03-26; source msha-controller-operator-history
- **operator_operates_mine:** Roark Coal Company → Wormey Coal No 4; 1985-03-27 to 1986-04-16; source msha-controller-operator-history
- **controller_controls_mine:** Roark Marvin-Jack Et Al → Wormey Coal No 4; 1985-03-27 to 1987-09-23; source msha-controller-operator-history
- **controller_controls_operator:** Roark Marvin-Jack Et Al → Roark Coal Company; 1985-03-27 to 1986-04-16; source msha-controller-operator-history
- **controller_controls_mine:** Taylor Mike → Wormey Coal No 4; 1985-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rouse Coal Company → Wormey Coal No 4; 1986-04-17 to 1986-09-01; source msha-controller-operator-history
- **controller_controls_mine:** Rouse James Sr Et Al → Wormey Coal No 4; 1986-04-17 to 1986-09-01; source msha-controller-operator-history
- **controller_controls_operator:** Rouse James Sr Et Al → Rouse Coal Company; 1986-04-17 to 1986-09-01; source msha-controller-operator-history
- **operator_operates_mine:** Wormey Coal Company → Wormey Coal No 4; 1986-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Taylor Mike → Wormey Coal Company; 1986-09-02 to current/open; source msha-controller-operator-history