# Relationship history for MSHA mine 0504647

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials → NORTHERN PORTABLE PLANT #15**

- 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 → NORTHERN PORTABLE PLANT #15; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → NORTHERN PORTABLE PLANT #15; 1998-02-11 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Western Mobile Northern Inc → NORTHERN PORTABLE PLANT #15; 1999-05-01 to 2002-01-30; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Western Mobile Northern Inc; 1999-05-01 to 2002-01-30; source msha-controller-operator-history
- **operator_operates_mine:** Lafarge West  Incorporated → NORTHERN PORTABLE PLANT #15; 2002-01-31 to 2011-12-20; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → NORTHERN PORTABLE PLANT #15; 2002-01-31 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Lafarge West  Incorporated; 2002-01-31 to 2011-12-20; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials → NORTHERN PORTABLE PLANT #15; 2011-12-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials; 2011-12-21 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → NORTHERN PORTABLE PLANT #15; 2015-07-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Lafarge West  Incorporated; 2015-07-10 to 2011-12-20; source msha-controller-operator-history