# Relationship history for MSHA mine 1515016

Current hierarchy: **Howard Laurence B Jr → Norton Coal Corp → Nortonville South 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

- **operator_operates_mine:** Norton Coal Corp → Nortonville South No 4; 1984-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Howard Laurence B Jr → Nortonville South No 4; 1984-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howard Laurence B Jr → Norton Coal Corp; 1984-12-01 to current/open; source msha-controller-operator-history