# Relationship history for MSHA mine 4503662

Current hierarchy: **Robert F  O'Brien → O'Brien Sand and Gravel Inc → O'Brien 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 F  O'Brien → O'Brien Quarry; 2006-07-26 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** O'Brien Sand and Gravel Inc → O'Brien Quarry; 2009-05-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert F  O'Brien → O'Brien Sand and Gravel Inc; 2009-05-05 to current/open; source msha-controller-operator-history