# Relationship history for MSHA mine 0901144

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc → Six Mile 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

- **controller_controls_mine:** Martin Marietta Materials Inc → Six Mile Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Florida Rock Industries Inc → Six Mile Quarry; 1950-01-01 to 2007-11-15; source msha-controller-operator-history
- **operator_operates_mine:** Florida Rock Industries Inc → Six Mile Quarry; 2001-11-01 to 2008-04-11; source msha-controller-operator-history
- **controller_controls_operator:** Florida Rock Industries Inc → Florida Rock Industries Inc; 2001-11-01 to 2007-11-15; source msha-controller-operator-history
- **controller_controls_mine:** Vulcan Materials Company → Six Mile Quarry; 2007-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vulcan Materials Company → Florida Rock Industries Inc; 2007-11-16 to 2008-04-11; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc → Six Mile Quarry; 2008-04-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials, Inc; 2008-04-12 to current/open; source msha-controller-operator-history