# Relationship history for MSHA mine 3608307

Current hierarchy: **Roger  Ohler → HARDROCK COAL COMPANY, INC. → HARDROCK COAL CO.**

- 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:** Hard Rock Coal Company → HARDROCK COAL CO.; 1992-01-01 to 2001-11-22; source msha-controller-operator-history
- **controller_controls_mine:** Roger  Ohler → HARDROCK COAL CO.; 1992-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roger  Ohler → Hard Rock Coal Company; 1992-01-01 to 2001-11-22; source msha-controller-operator-history
- **operator_operates_mine:** Hard Rock Coal Co. → HARDROCK COAL CO.; 2001-11-23 to 2003-09-01; source msha-controller-operator-history
- **controller_controls_mine:** Jody L  Ritchie → HARDROCK COAL CO.; 2001-11-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jody L  Ritchie → Hard Rock Coal Co.; 2001-11-23 to 2003-09-01; source msha-controller-operator-history
- **operator_operates_mine:** Hardrock Coal Company, Inc. → HARDROCK COAL CO.; 2003-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roger  Ohler → Hardrock Coal Company, Inc.; 2003-09-02 to current/open; source msha-controller-operator-history