# Relationship history for MSHA mine 1800579

Current hierarchy: **Thomson Norman → L C Coal Company Inc → Ashby/Caldwell Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Thomson Norman → Ashby/Caldwell Mine; 1974-08-05 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** L C Coal Company Inc → Ashby/Caldwell Mine; 1975-07-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomson Norman → L C Coal Company Inc; 1975-07-29 to current/open; source msha-controller-operator-history