# Relationship history for MSHA mine 0504735

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials → Northern Portable Plant #17**

- 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 #17; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Lafarge West Incorporated → Northern Portable Plant #17; 2002-01-31 to 2011-12-20; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → Northern Portable Plant #17; 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 #17; 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 #17; 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