# Relationship history for MSHA mine 2200535

Current hierarchy: **Lawrence W  Warren → Williams Gravel Company → CROWN ZELLERBACH 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

- **operator_operates_mine:** Williams Gravel Company Inc → CROWN ZELLERBACH PIT; 1981-06-01 to 1983-01-27; source msha-controller-operator-history
- **controller_controls_mine:** Williams C S → CROWN ZELLERBACH PIT; 1981-06-01 to 1983-01-27; source msha-controller-operator-history
- **controller_controls_operator:** Williams C S → Williams Gravel Company Inc; 1981-06-01 to 1983-01-27; source msha-controller-operator-history
- **operator_operates_mine:** Williams Gravel Company → CROWN ZELLERBACH PIT; 1983-01-28 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lawrence W  Warren → CROWN ZELLERBACH PIT; 1983-01-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lawrence W  Warren → Williams Gravel Company; 1983-01-28 to current/open; source msha-controller-operator-history