# Relationship history for MSHA mine 1600971

Current hierarchy: **Bobby G  Johnson → Industrial Gravel Company Inc → Hatcher 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Industrial Gravel Inc → Hatcher Pit; 1979-12-01 to 1981-07-26; source msha-controller-operator-history
- **controller_controls_mine:** Pipes Randolph → Hatcher Pit; 1979-12-01 to 1981-07-26; source msha-controller-operator-history
- **controller_controls_operator:** Pipes Randolph → Industrial Gravel Inc; 1979-12-01 to 1981-07-26; source msha-controller-operator-history
- **operator_operates_mine:** Industrial Gravel Company Inc → Hatcher Pit; 1981-07-27 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bobby G  Johnson → Hatcher Pit; 1981-07-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bobby G  Johnson → Industrial Gravel Company Inc; 1981-07-27 to current/open; source msha-controller-operator-history