# Relationship history for MSHA mine 5001881

Current hierarchy: **Bering Straits Native Corporation → Sound Quarry Inc. → Sound Quarry Rock Sorter**

- 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:** Lynden Inc → Sound Quarry Rock Sorter; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Knik Construction Co., Inc. → Sound Quarry Rock Sorter; 2008-06-09 to 2018-09-16; source msha-controller-operator-history
- **controller_controls_operator:** Lynden Inc → Knik Construction Co., Inc.; 2008-06-09 to 2018-09-16; source msha-controller-operator-history
- **operator_operates_mine:** Sound Quarry Inc. → Sound Quarry Rock Sorter; 2018-09-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bering Straits Native Corporation → Sound Quarry Rock Sorter; 2018-09-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bering Straits Native Corporation → Sound Quarry Inc.; 2018-09-17 to current/open; source msha-controller-operator-history