# Relationship history for MSHA mine 1600464

Current hierarchy: **Dravo Corp → Dravo Basic Materials Company Inc → Dredge Avocet**

- 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:** Radcliff Materials Inc → Dredge Avocet; 1950-01-01 to 1979-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Southern Industries Inc → Dredge Avocet; 1950-01-01 to 1979-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Southern Industries Inc → Radcliff Materials Inc; 1950-01-01 to 1979-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Dravo Corp → Dredge Avocet; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Dravo Basic Materials Company Inc → Dredge Avocet; 1979-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dravo Corp → Dravo Basic Materials Company Inc; 1979-06-01 to current/open; source msha-controller-operator-history