# Relationship history for MSHA mine 2002344

Current hierarchy: **Brent  Gerken; Michael J  Gerken → Gerken Materials Inc → Gerken Materials- Hillsdale Plant**

- 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

- **operator_operates_mine:** Hillsdale Sand & Gravel Inc → Gerken Materials- Hillsdale Plant; 1950-01-01 to 2008-09-28; source msha-controller-operator-history
- **controller_controls_mine:** Dean E Miller → Gerken Materials- Hillsdale Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dean E Miller → Hillsdale Sand & Gravel Inc; 1950-01-01 to 2008-09-28; source msha-controller-operator-history
- **controller_controls_mine:** Brent  Gerken et al → Gerken Materials- Hillsdale Plant; 2008-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Gerken Materials Inc → Gerken Materials- Hillsdale Plant; 2008-09-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brent  Gerken et al → Gerken Materials Inc; 2008-09-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael J  Gerken et al → Gerken Materials Inc; 2008-09-29 to current/open; source msha-controller-operator-history