# Relationship history for MSHA mine 2500013

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Corp → Auburn Quarry**

- 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:** Hopper Brothers Quarries → Auburn Quarry; 1950-01-01 to 1980-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Hopper Chester & Raymond → Auburn Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hopper Chester & Raymond → Hopper Brothers Quarries; 1950-01-01 to 1980-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Auburn Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Corp → Auburn Quarry; 1980-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Corp; 1980-08-01 to current/open; source msha-controller-operator-history