# Relationship history for MSHA mine 4604342

Current hierarchy: **Secrist Holly R → Rock Run Coal Company Inc → Big-Un No 1 Mine**

- 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:** Occidental Petroleum Corp → Big-Un No 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Island Creek Coal Company → Big-Un No 1 Mine; 1974-10-13 to 1990-10-14; source msha-controller-operator-history
- **controller_controls_operator:** Occidental Petroleum Corp → Island Creek Coal Company; 1974-10-13 to 1990-10-14; source msha-controller-operator-history
- **operator_operates_mine:** Rock Run Coal Company Inc → Big-Un No 1 Mine; 1990-10-15 to 1991-02-28; source msha-controller-operator-history
- **controller_controls_mine:** Workman Wilma A → Big-Un No 1 Mine; 1990-10-15 to 1991-02-28; source msha-controller-operator-history
- **controller_controls_operator:** Workman Wilma A → Rock Run Coal Company Inc; 1990-10-15 to 1991-02-28; source msha-controller-operator-history
- **operator_operates_mine:** Rock Run Coal Company Inc → Big-Un No 1 Mine; 1991-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Secrist Holly R → Big-Un No 1 Mine; 1991-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Secrist Holly R → Rock Run Coal Company Inc; 1991-03-01 to current/open; source msha-controller-operator-history