# Relationship history for MSHA mine 4606253

Current hierarchy: **Keenan Darrell R → First Big Mountain Mining Company Inc → Prep Plant 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:** Ferguson William G & Eugene S Sikora → Prep Plant No 1; 1979-10-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Keenan Darrell R → Prep Plant No 1; 1980-08-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Witcher Creek Coal Company Inc → Prep Plant No 1; 1980-10-01 to 1985-04-21; source msha-controller-operator-history
- **controller_controls_operator:** Ferguson William G & Eugene S Sikora → Witcher Creek Coal Company Inc; 1980-10-01 to 1985-04-21; source msha-controller-operator-history
- **operator_operates_mine:** Witcher Mining Corp → Prep Plant No 1; 1985-04-22 to 1987-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Grubb M W Jr → Prep Plant No 1; 1985-04-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grubb M W Jr → Witcher Mining Corp; 1985-04-22 to 1987-04-30; source msha-controller-operator-history
- **operator_operates_mine:** First Big Mountain Mining Company Inc → Prep Plant No 1; 1987-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Keenan Darrell R → First Big Mountain Mining Company Inc; 1987-05-01 to current/open; source msha-controller-operator-history