# Relationship history for MSHA mine 3603509

Current hierarchy: **Matthew G  Markunas → Central Builders Supply Company → Northumberland Sand 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Central Builders Supply Company → Northumberland Sand Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Anthony B  Markunas → Northumberland Sand Plant; 1950-01-01 to 2024-02-18; source msha-controller-operator-history
- **controller_controls_operator:** Anthony B  Markunas → Central Builders Supply Company; 1950-01-01 to 2024-02-18; source msha-controller-operator-history
- **controller_controls_mine:** Matthew G  Markunas → Northumberland Sand Plant; 2024-02-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Matthew G  Markunas → Central Builders Supply Company; 2024-02-19 to current/open; source msha-controller-operator-history