# Relationship history for MSHA mine 0503942

Current hierarchy: **Vernie  Houtchens → Midway Sand & Gravel Inc → Midway Gravel Quarry**

- 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:** Rock Lock Inc → Midway Gravel Quarry; 1984-04-01 to 1988-04-24; source msha-controller-operator-history
- **controller_controls_mine:** Dale S  Andersen → Midway Gravel Quarry; 1984-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dale S  Andersen → Rock Lock Inc; 1984-04-01 to 1988-04-24; source msha-controller-operator-history
- **operator_operates_mine:** Midway Sand & Gravel Inc → Midway Gravel Quarry; 1988-04-25 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Vernie  Houtchens → Midway Gravel Quarry; 1988-04-25 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vernie  Houtchens → Midway Sand & Gravel Inc; 1988-04-25 to current/open; source msha-controller-operator-history