# Relationship history for MSHA mine 2500923

Current hierarchy: **Olson Verna → Ayres Sand & Gravel → Ayres Sand And Gravel 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Ayres Sand & Gravel → Ayres Sand And Gravel Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Olson Verna → Ayres Sand And Gravel Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Olson Verna → Ayres Sand & Gravel; 1979-01-01 to current/open; source msha-controller-operator-history