# Relationship history for MSHA mine 1701120

Current hierarchy: **Nick M  Curtis → Curtis Sand & Gravel → Astec Screener GT205S 2022**

- 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

- **controller_controls_mine:** Nick M  Curtis → Astec Screener GT205S 2022; 2022-05-13 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Curtis Sand & Gravel → Astec Screener GT205S 2022; 2024-05-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nick M  Curtis → Curtis Sand & Gravel; 2024-05-28 to current/open; source msha-controller-operator-history