# Relationship history for MSHA mine 4702420

Current hierarchy: **Paul  Duffek; Calvin  Krueger → Duffek Sand & Gravel Inc → Plant #2 (Telesmith)**

- 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:** Duffek Sand & Gravel Inc → Plant #2 (Telesmith); 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Paul  Duffek  et al → Plant #2 (Telesmith); 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Paul  Duffek  et al → Duffek Sand & Gravel Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Calvin  Krueger  et al → Duffek Sand & Gravel Inc; 1950-01-01 to current/open; source msha-controller-operator-history