# Relationship history for MSHA mine 1515168

Current hierarchy: **A Y  Evans; Eugene  Gambrell → Evans & Gambrel Coal Inc → No 2 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:** Eugene  Gambrell et al → No 2 Surface; 1977-11-15 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Evans & Gambrel Coal Inc → No 2 Surface; 1985-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Eugene  Gambrell et al → Evans & Gambrel Coal Inc; 1985-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** A Y  Evans et al → Evans & Gambrel Coal Inc; 1985-04-01 to current/open; source msha-controller-operator-history