# Relationship history for MSHA mine 4001857

Current hierarchy: **Seiber Robert H → Walden Ridge Coal Company → No 1 Surface**

- 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

- **operator_operates_mine:** P & C Coal Company → No 1 Surface; 1975-09-01 to 1976-10-18; source msha-controller-operator-history
- **controller_controls_mine:** Cates Carel & Gorden Pickle → No 1 Surface; 1975-09-01 to 1976-10-18; source msha-controller-operator-history
- **controller_controls_operator:** Cates Carel & Gorden Pickle → P & C Coal Company; 1975-09-01 to 1976-10-18; source msha-controller-operator-history
- **operator_operates_mine:** Walden Ridge Coal Company → No 1 Surface; 1976-10-19 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Seiber Robert H → No 1 Surface; 1976-10-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Seiber Robert H → Walden Ridge Coal Company; 1976-10-19 to current/open; source msha-controller-operator-history