# Relationship history for MSHA mine 4501999

Current hierarchy: **Heidelberg Materials AG → HM Pacific Northwest, Inc. → Heidelberg Materials High Rock 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

- **operator_operates_mine:** Industrial Rock Products Inc → Heidelberg Materials High Rock Quarry; 1950-01-01 to 1984-10-04; source msha-controller-operator-history
- **controller_controls_mine:** Albert J  Firchau → Heidelberg Materials High Rock Quarry; 1950-01-01 to 1984-10-04; source msha-controller-operator-history
- **controller_controls_operator:** Albert J  Firchau → Industrial Rock Products Inc; 1950-01-01 to 1984-10-04; source msha-controller-operator-history
- **operator_operates_mine:** Cadman Rock Company Inc → Heidelberg Materials High Rock Quarry; 1984-10-05 to 1991-01-01; source msha-controller-operator-history
- **controller_controls_mine:** Paul J  Taylor  et al → Heidelberg Materials High Rock Quarry; 1984-10-05 to 1991-01-01; source msha-controller-operator-history
- **controller_controls_operator:** Paul J  Taylor  et al → Cadman Rock Company Inc; 1984-10-05 to 1991-01-01; source msha-controller-operator-history
- **operator_operates_mine:** Cadman (Rock) Inc → Heidelberg Materials High Rock Quarry; 1991-01-02 to 2023-01-30; source msha-controller-operator-history
- **controller_controls_mine:** Cimenteries Cbr Cementbedrijven → Heidelberg Materials High Rock Quarry; 1991-01-02 to 2000-07-20; source msha-controller-operator-history
- **controller_controls_operator:** Cimenteries Cbr Cementbedrijven → Cadman (Rock) Inc; 1991-01-02 to 2000-07-20; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → Heidelberg Materials High Rock Quarry; 2000-07-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Cadman (Rock) Inc; 2000-07-21 to 2023-01-30; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → Heidelberg Materials High Rock Quarry; 2017-06-30 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** HM Pacific Northwest, Inc. → Heidelberg Materials High Rock Quarry; 2023-01-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → HM Pacific Northwest, Inc.; 2023-01-31 to current/open; source msha-controller-operator-history