# Relationship history for MSHA mine 4501153

Current hierarchy: **Ronald M  Wamberg → Columbia Rock & Aggregates Inc → Mill Plain Pit & Plant**

- 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:** Columbia Rock & Aggregates Inc → Mill Plain Pit & Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ronald M  Wamberg  et al → Mill Plain Pit & Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ronald M  Wamberg  et al → Columbia Rock & Aggregates Inc; 1950-01-01 to current/open; source msha-controller-operator-history