# Relationship history for MSHA mine 1506806

Current hierarchy: **Pemberton Herb → P & P 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:** Pemberton & Bolton Coal Company → No 1 Surface; 1973-01-01 to 1975-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Pemberton Herb → No 1 Surface; 1973-01-01 to 1975-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Pemberton Herb → Pemberton & Bolton Coal Company; 1973-01-01 to 1975-04-30; source msha-controller-operator-history
- **operator_operates_mine:** P & P Coal Company → No 1 Surface; 1975-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Pemberton Herb → No 1 Surface; 1975-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Pemberton Herb → P & P Coal Company; 1975-05-01 to current/open; source msha-controller-operator-history