# Relationship history for MSHA mine 0505167

Current hierarchy: **George  Zadel → Northern Colorado Constructors → Irwin Thomas**

- 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:** George  Zadel Et Al → Irwin Thomas; 2004-04-20 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Northern Colorado Constructors → Irwin Thomas; 2023-03-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** George  Zadel Et Al → Northern Colorado Constructors; 2023-03-27 to current/open; source msha-controller-operator-history