# Relationship history for MSHA mine 4405975

Current hierarchy: **Chadwick William D → Saltville Silica Inc → No 1 Open Pit Silica Sand**

- 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:** Saltville Silica Inc → No 1 Open Pit Silica Sand; 1983-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Chadwick William D → No 1 Open Pit Silica Sand; 1983-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chadwick William D → Saltville Silica Inc; 1983-01-01 to current/open; source msha-controller-operator-history