# Relationship history for MSHA mine 3607343

Current hierarchy: **Erdley Olivia A → H & R Coal Company → Martz Mine**

- 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:** H & R Coal Company → Martz Mine; 1982-07-01 to 1984-07-17; source msha-controller-operator-history
- **controller_controls_mine:** Duncan Randy C → Martz Mine; 1982-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Duncan Randy C → H & R Coal Company; 1982-07-01 to 1984-07-17; source msha-controller-operator-history
- **operator_operates_mine:** H & R Coal Company → Martz Mine; 1984-07-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Erdley Olivia A → Martz Mine; 1984-07-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Erdley Olivia A → H & R Coal Company; 1984-07-18 to current/open; source msha-controller-operator-history