# Relationship history for MSHA mine 1001790

Current hierarchy: **Rick S  Thomas → Thomas Ranch Gravel → Thomas Ranch Pit**

- 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:** Thomas Ranch → Thomas Ranch Pit; 1987-06-01 to 1993-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Preston  Thomas → Thomas Ranch Pit; 1987-06-01 to 1993-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Preston  Thomas → Thomas Ranch; 1987-06-01 to 1993-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Thomas Ranch Gravel → Thomas Ranch Pit; 1993-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rick S  Thomas → Thomas Ranch Pit; 1993-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rick S  Thomas → Thomas Ranch Gravel; 1993-06-01 to current/open; source msha-controller-operator-history