# Relationship history for MSHA mine 1600962

Current hierarchy: **Bailey Melvin → B & B Sand & Gravel → Bailey Dredge**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** David E  Joshlin → Bailey Dredge; 1950-01-01 to 1981-09-01; source msha-controller-operator-history
- **operator_operates_mine:** Gravel Production Company → Bailey Dredge; 1980-01-01 to 1981-09-01; source msha-controller-operator-history
- **controller_controls_operator:** David E  Joshlin → Gravel Production Company; 1980-01-01 to 1981-09-01; source msha-controller-operator-history
- **operator_operates_mine:** B & B Sand & Gravel → Bailey Dredge; 1981-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bailey Melvin → Bailey Dredge; 1981-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bailey Melvin → B & B Sand & Gravel; 1981-09-02 to current/open; source msha-controller-operator-history