# Relationship history for MSHA mine 4801751

Current hierarchy: **Tolsa S A → Tolsa Wyoming Bentonite → Tolsa Wyoming Bentonite Plant**

- 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:** US Bentonite Processing, Inc → Tolsa Wyoming Bentonite Plant; 2010-10-14 to 2015-02-19; source msha-controller-operator-history
- **controller_controls_mine:** Robert  Nolind et al → Tolsa Wyoming Bentonite Plant; 2010-10-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert  Nolind et al → US Bentonite Processing, Inc; 2010-10-14 to 2015-02-19; source msha-controller-operator-history
- **operator_operates_mine:** Tolsa Wyoming Bentonite → Tolsa Wyoming Bentonite Plant; 2015-02-20 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tolsa S A → Tolsa Wyoming Bentonite Plant; 2015-02-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tolsa S A → Tolsa Wyoming Bentonite; 2015-02-20 to current/open; source msha-controller-operator-history