# Relationship history for MSHA mine 2602249

Current hierarchy: **Don F  Ahern → Rock City → NIPTON/ROCK CITY**

- 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:** Rock City → NIPTON/ROCK CITY; 1994-04-01 to 1998-01-07; source msha-controller-operator-history
- **controller_controls_mine:** Don L  Woolbright → NIPTON/ROCK CITY; 1994-04-01 to 1998-01-07; source msha-controller-operator-history
- **controller_controls_operator:** Don L  Woolbright → Rock City; 1994-04-01 to 1998-01-07; source msha-controller-operator-history
- **operator_operates_mine:** Rock City → NIPTON/ROCK CITY; 1998-01-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Don F  Ahern → NIPTON/ROCK CITY; 1998-01-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Don F  Ahern → Rock City; 1998-01-08 to current/open; source msha-controller-operator-history