# Relationship history for MSHA mine 4608021

Current hierarchy: **Brock Mining Inc → Brock Mining Inc → Brock No 1**

- 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:** Ashland Inc et al → Brock No 1; 1989-08-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Red River Valley Coal Company → Brock No 1; 1991-04-01 to 1992-09-20; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc et al → Red River Valley Coal Company; 1991-04-01 to 1992-09-20; source msha-controller-operator-history
- **operator_operates_mine:** Brock Mining Inc → Brock No 1; 1992-09-21 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brock Mining Inc → Brock No 1; 1992-09-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brock Mining Inc → Brock Mining Inc; 1992-09-21 to current/open; source msha-controller-operator-history