# Relationship history for MSHA mine 4605724

Current hierarchy: **Sheppard Don → Westwood Coal Corp → Westwppd Coal 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:** Walsh David E → Westwppd Coal No 1 Mine; 1976-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Concord Coal Corp → Westwppd Coal No 1 Mine; 1978-02-01 to 1980-09-15; source msha-controller-operator-history
- **controller_controls_operator:** Walsh David E → Concord Coal Corp; 1978-02-01 to 1980-09-15; source msha-controller-operator-history
- **operator_operates_mine:** Westwood Coal Corp → Westwppd Coal No 1 Mine; 1980-09-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Sheppard Don → Westwppd Coal No 1 Mine; 1980-09-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sheppard Don → Westwood Coal Corp; 1980-09-16 to current/open; source msha-controller-operator-history