# Relationship history for MSHA mine 3304411

Current hierarchy: **Julian A  Gerken → Gerken Materials Inc → PORT CLINTON STONE YD.**

- 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

- **controller_controls_mine:** Julian A  Gerken → PORT CLINTON STONE YD.; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Gerken Materials Inc → PORT CLINTON STONE YD.; 1998-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Julian A  Gerken → Gerken Materials Inc; 1998-02-01 to current/open; source msha-controller-operator-history