# Relationship history for MSHA mine 1001950

Current hierarchy: **Gayhard L  Ruschman → Ruschman Sand & Gravel Inc → Pleasant Valley Pit**

- 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

- **controller_controls_mine:** Gayhard L  Ruschman → Pleasant Valley Pit; 1990-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ruschman Sand & Gravel Inc → Pleasant Valley Pit; 1999-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gayhard L  Ruschman → Ruschman Sand & Gravel Inc; 1999-03-01 to current/open; source msha-controller-operator-history