# Relationship history for MSHA mine 1516978

Current hierarchy: **Williams Ireland → W & A Coal Sales Inc → Mine #2**

- 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:** Rocky Ridge Coal Inc → Mine #2; 1990-09-01 to 1991-08-12; source msha-controller-operator-history
- **controller_controls_mine:** Duncan Kay → Mine #2; 1990-09-01 to 1991-08-12; source msha-controller-operator-history
- **controller_controls_operator:** Duncan Kay → Rocky Ridge Coal Inc; 1990-09-01 to 1991-08-12; source msha-controller-operator-history
- **controller_controls_mine:** Williams Ireland → Mine #2; 1991-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** W & A Coal Sales Inc → Mine #2; 1991-08-13 to 1992-10-19; source msha-controller-operator-history
- **controller_controls_operator:** Williams Ireland → W & A Coal Sales Inc; 1991-08-13 to 1992-10-19; source msha-controller-operator-history
- **operator_operates_mine:** M & G Transportation & Coal Sales Inc → Mine #2; 1992-10-20 to 1992-10-20; source msha-controller-operator-history
- **controller_controls_mine:** Meral  Williams et al → Mine #2; 1992-10-20 to 1992-10-20; source msha-controller-operator-history
- **controller_controls_operator:** Meral  Williams et al → M & G Transportation & Coal Sales Inc; 1992-10-20 to 1992-10-20; source msha-controller-operator-history
- **operator_operates_mine:** W & A Coal Sales Inc → Mine #2; 1992-10-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Williams Ireland → W & A Coal Sales Inc; 1992-10-21 to current/open; source msha-controller-operator-history