# Relationship history for MSHA mine 1300750

Current hierarchy: **Chad  Van Zee → Valley Sand & Gravel → Valley Sand and 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:** Rock Valley Cement Block & Tile Inc → Valley Sand and Gravel; 1950-01-01 to 2002-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Chad  Van Zee → Valley Sand and Gravel; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chad  Van Zee → Rock Valley Cement Block & Tile Inc; 1950-01-01 to 2002-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Valley Sand & Gravel → Valley Sand and Gravel; 2002-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Chad  Van Zee → Valley Sand and Gravel; 2002-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chad  Van Zee → Valley Sand & Gravel; 2002-04-01 to current/open; source msha-controller-operator-history