# Relationship history for MSHA mine 3609480

Current hierarchy: **Robert K  Volk → Arrowhead Quarries → Curley Quarry**

- 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:** Robert K  Volk → Curley Quarry; 2004-04-22 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Arrowhead Quarries → Curley Quarry; 2006-10-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert K  Volk → Arrowhead Quarries; 2006-10-31 to current/open; source msha-controller-operator-history