# Relationship history for MSHA mine 4503324

Current hierarchy: **Vellema Clark → Snohomish Excavators → SNOHOMISH SAND & GRAVEL**

- 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

- **operator_operates_mine:** Snohomish Excavators → SNOHOMISH SAND & GRAVEL; 1994-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Vellema Clark → SNOHOMISH SAND & GRAVEL; 1994-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vellema Clark → Snohomish Excavators; 1994-08-01 to current/open; source msha-controller-operator-history