# Relationship history for MSHA mine 1400220

Current hierarchy: **Duffy J P → Humboldt Brick & Tile Company → Humboldt Clay 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:** Humboldt Brick & Tile Company → Humboldt Clay Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Duffy J P → Humboldt Clay Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Duffy J P → Humboldt Brick & Tile Company; 1950-01-01 to current/open; source msha-controller-operator-history