# Relationship history for MSHA mine 1508270

Current hierarchy: **Townley Lynn → B B & T Minerals → 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

- **controller_controls_mine:** Williams & Crabtree Construction Company Inc → No 1 Surface; 1975-03-05 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Williams & Crabtree Construction Company Inc → No 1 Surface; 1975-04-21 to 1977-04-18; source msha-controller-operator-history
- **controller_controls_operator:** Williams & Crabtree Construction Company Inc → Williams & Crabtree Construction Company Inc; 1975-04-21 to 1977-04-18; source msha-controller-operator-history
- **controller_controls_mine:** Townley Lynn → No 1 Surface; 1976-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** B B & T Minerals → No 1 Surface; 1977-04-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Townley Lynn → B B & T Minerals; 1977-04-19 to current/open; source msha-controller-operator-history