# Relationship history for MSHA mine 3502761

Current hierarchy: **Lonny  Bessett → Portable Rock Production Company Inc → Portable Rock Production Co. Sears 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:** Lonny  Bessett → Portable Rock Production Co. Sears Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Zumwalt & Williams Sand & Gravel Inc → Portable Rock Production Co. Sears Pit; 1950-01-01 to 1979-12-11; source msha-controller-operator-history
- **controller_controls_mine:** Jim  Williams → Portable Rock Production Co. Sears Pit; 1950-01-01 to 1992-02-25; source msha-controller-operator-history
- **controller_controls_operator:** Jim  Williams → Zumwalt & Williams Sand & Gravel Inc; 1950-01-01 to 1979-12-11; source msha-controller-operator-history
- **operator_operates_mine:** Portable Rock Production Company Inc → Portable Rock Production Co. Sears Pit; 1979-12-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lonny  Bessett → Portable Rock Production Company Inc; 1979-12-12 to current/open; source msha-controller-operator-history