# Relationship history for MSHA mine 4502851

Current hierarchy: **Montgomery Harold → Montgomery-Nordhougen Inc → Canton Creek 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Montgomery Harold → Canton Creek Quarry; 1979-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Montgomery-Nordhougen Inc → Canton Creek Quarry; 1981-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Montgomery Harold → Montgomery-Nordhougen Inc; 1981-05-01 to current/open; source msha-controller-operator-history