# Relationship history for MSHA mine 2103851

Current hierarchy: **Knife River Corporation → Strata Corporation → Portable Plant #10**

- 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:** James R  Bradshaw et al → Portable Plant #10; 1950-01-01 to 2026-03-22; source msha-controller-operator-history
- **operator_operates_mine:** Summit Sand and Gravel, Inc. → Portable Plant #10; 2015-03-31 to 2017-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Christopher C  West et al → Portable Plant #10; 2015-03-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Christopher C  West et al → Summit Sand and Gravel, Inc.; 2015-03-31 to 2017-07-31; source msha-controller-operator-history
- **controller_controls_operator:** Jeff T  Rehder et al → Summit Sand and Gravel, Inc.; 2015-03-31 to 2017-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Strata Corporation → Portable Plant #10; 2017-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James R  Bradshaw et al → Strata Corporation; 2017-08-01 to 2026-03-22; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → Portable Plant #10; 2026-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Strata Corporation; 2026-03-23 to current/open; source msha-controller-operator-history