# Relationship history for MSHA mine 1201509

Current hierarchy: **Willoughby Delbert E → Walesboro Gravel Company → Walesboro Gravel Company**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Columbus Gravel & Concrete Products Inc → Walesboro Gravel Company; 1950-01-01 to 1983-10-13; source msha-controller-operator-history
- **controller_controls_mine:** Boas Joe E → Walesboro Gravel Company; 1950-01-01 to 1983-10-13; source msha-controller-operator-history
- **controller_controls_operator:** Boas Joe E → Columbus Gravel & Concrete Products Inc; 1950-01-01 to 1983-10-13; source msha-controller-operator-history
- **operator_operates_mine:** Walesboro Gravel Company Inc → Walesboro Gravel Company; 1983-10-14 to 1985-12-08; source msha-controller-operator-history
- **controller_controls_mine:** Smith Dennis I → Walesboro Gravel Company; 1983-10-14 to 1985-12-08; source msha-controller-operator-history
- **controller_controls_operator:** Smith Dennis I → Walesboro Gravel Company Inc; 1983-10-14 to 1985-12-08; source msha-controller-operator-history
- **operator_operates_mine:** Walesboro Gravel Company → Walesboro Gravel Company; 1985-12-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Willoughby Delbert E → Walesboro Gravel Company; 1985-12-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Willoughby Delbert E → Walesboro Gravel Company; 1985-12-09 to current/open; source msha-controller-operator-history