# Relationship history for MSHA mine 2301672

Current hierarchy: **Fredrick Marvin → Marvin Fredrick Sand & Gravel → Marvin Fredrick Sand And Gravel**

- 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:** F & S Gravel Company → Marvin Fredrick Sand And Gravel; 1950-01-01 to 1978-04-01; source msha-controller-operator-history
- **controller_controls_mine:** F & S Gravel Company → Marvin Fredrick Sand And Gravel; 1950-01-01 to 1978-04-01; source msha-controller-operator-history
- **controller_controls_operator:** F & S Gravel Company → F & S Gravel Company; 1950-01-01 to 1978-04-01; source msha-controller-operator-history
- **operator_operates_mine:** Marvin Fredrick Sand & Gravel → Marvin Fredrick Sand And Gravel; 1978-04-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Fredrick Marvin → Marvin Fredrick Sand And Gravel; 1978-04-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Fredrick Marvin → Marvin Fredrick Sand & Gravel; 1978-04-02 to current/open; source msha-controller-operator-history