# Relationship history for MSHA mine 1302127

Current hierarchy: **Donald  Dusek; Ken  Dusek → Dusek Sand & Gravel Ltd → DUSEK SAND & GRAVEL LTD.**

- 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:** Tiefenthaler Dean → DUSEK SAND & GRAVEL LTD.; 1984-12-01 to 2006-02-12; source msha-controller-operator-history
- **operator_operates_mine:** Carnarvon Sand & Gravel Inc → DUSEK SAND & GRAVEL LTD.; 1985-07-01 to 1992-04-27; source msha-controller-operator-history
- **controller_controls_operator:** Tiefenthaler Dean → Carnarvon Sand & Gravel Inc; 1985-07-01 to 1992-04-27; source msha-controller-operator-history
- **operator_operates_mine:** Blackhawk Rock & Gravel Inc → DUSEK SAND & GRAVEL LTD.; 1992-04-28 to 1997-04-06; source msha-controller-operator-history
- **controller_controls_mine:** Larson Richard T → DUSEK SAND & GRAVEL LTD.; 1992-04-28 to 1997-04-06; source msha-controller-operator-history
- **controller_controls_operator:** Larson Richard T → Blackhawk Rock & Gravel Inc; 1992-04-28 to 1997-04-06; source msha-controller-operator-history
- **controller_controls_mine:** Ken  Dusek  et al → DUSEK SAND & GRAVEL LTD.; 1997-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Dusek Sand & Gravel Ltd → DUSEK SAND & GRAVEL LTD.; 1997-04-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ken  Dusek  et al → Dusek Sand & Gravel Ltd; 1997-04-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald  Dusek  et al → Dusek Sand & Gravel Ltd; 1997-04-07 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John J  Healey → DUSEK SAND & GRAVEL LTD.; 2006-02-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John J  Healey → Carnarvon Sand & Gravel Inc; 2006-02-13 to 1992-04-27; source msha-controller-operator-history