# Relationship history for MSHA mine 4002664

Current hierarchy: **Sweat Clarence → Gray Ridge Mining Inc → 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:** Day Ules → No 1 Surface; 1979-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Iron Ridge Fuels Inc → No 1 Surface; 1981-01-01 to 1981-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Day Ules → Iron Ridge Fuels Inc; 1981-01-01 to 1981-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Gray Ridge Mining Inc → No 1 Surface; 1981-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Sweat Clarence → No 1 Surface; 1981-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sweat Clarence → Gray Ridge Mining Inc; 1981-04-01 to current/open; source msha-controller-operator-history