# Relationship history for MSHA mine 1507988

Current hierarchy: **Wheeler E F Sr → Giant Earthmovers Inc → G E M 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:** Giant Earthmovers Inc → G E M No 1 Surface; 1974-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Wheeler E F Sr → G E M No 1 Surface; 1974-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wheeler E F Sr → Giant Earthmovers Inc; 1974-10-01 to current/open; source msha-controller-operator-history