# Relationship history for MSHA mine 0901037

Current hierarchy: **Mearl Corp → Mearl Corp Sfm Division → Hartwell 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:** Mearl Corp Sfm Division → Hartwell Sand Plant; 1989-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mearl Corp → Hartwell Sand Plant; 1989-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mearl Corp → Mearl Corp Sfm Division; 1989-02-01 to current/open; source msha-controller-operator-history