# Relationship history for MSHA mine 4702606

Current hierarchy: **Michael R  Harriage → Northern Gravel Company → Northern Gravel Company Pit**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Northern Paper Recycling Company Inc → Northern Gravel Company Pit; 1979-01-01 to 1981-12-06; source msha-controller-operator-history
- **controller_controls_mine:** Neuenschwander Roger A → Northern Gravel Company Pit; 1979-01-01 to 1981-12-06; source msha-controller-operator-history
- **controller_controls_operator:** Neuenschwander Roger A → Northern Paper Recycling Company Inc; 1979-01-01 to 1981-12-06; source msha-controller-operator-history
- **operator_operates_mine:** Northern Gravel Company → Northern Gravel Company Pit; 1981-12-07 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael R  Harriage  et al → Northern Gravel Company Pit; 1981-12-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael R  Harriage  et al → Northern Gravel Company; 1981-12-07 to current/open; source msha-controller-operator-history