# Relationship history for MSHA mine 4703951

Current hierarchy: **Greg  Kolodziej → North Central Aggregates → Portable Screen #1**

- 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:** Thomas G  Kolodziej  et al → Portable Screen #1; 1989-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Iron River Sand and Gravel → Portable Screen #1; 2024-03-01 to 2024-11-30; source msha-controller-operator-history
- **controller_controls_operator:** Thomas G  Kolodziej  et al → Iron River Sand and Gravel; 2024-03-01 to 2024-11-30; source msha-controller-operator-history
- **controller_controls_operator:** Barbara C  Kolodziej et al → Iron River Sand and Gravel; 2024-03-01 to 2024-11-30; source msha-controller-operator-history
- **operator_operates_mine:** North Central Aggregates → Portable Screen #1; 2024-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Greg  Kolodziej → Portable Screen #1; 2024-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Greg  Kolodziej → North Central Aggregates; 2024-12-01 to current/open; source msha-controller-operator-history