# Relationship history for MSHA mine 3304168

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Aggregates → SPRING VALLEY NORTH-593**

- 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

- **controller_controls_mine:** Martin Marietta Materials Inc → SPRING VALLEY NORTH-593; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ronald E  Watson → SPRING VALLEY NORTH-593; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Watson Gravel Inc → SPRING VALLEY NORTH-593; 1989-06-01 to 1998-06-10; source msha-controller-operator-history
- **controller_controls_operator:** Ronald E  Watson → Watson Gravel Inc; 1989-06-01 to 1998-06-10; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Aggregates → SPRING VALLEY NORTH-593; 1998-06-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates; 1998-06-11 to current/open; source msha-controller-operator-history