# Relationship history for MSHA mine 0504418

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials → Platte Sand and Gravel**

- 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 → Platte Sand and Gravel; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Henry  Braly → Platte Sand and Gravel; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Redland Plc → Platte Sand and Gravel; 1988-06-14 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Frontier Materials → Platte Sand and Gravel; 1990-02-01 to 1991-07-07; source msha-controller-operator-history
- **controller_controls_operator:** Henry  Braly → Frontier Materials; 1990-02-01 to 1991-07-07; source msha-controller-operator-history
- **operator_operates_mine:** Western Mobile Boulder Inc → Platte Sand and Gravel; 1991-07-08 to 1998-02-10; source msha-controller-operator-history
- **controller_controls_operator:** Redland Plc → Western Mobile Boulder Inc; 1991-07-08 to 1998-02-10; source msha-controller-operator-history
- **operator_operates_mine:** Western Mobile Inc → Platte Sand and Gravel; 1998-02-11 to 2002-01-30; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → Platte Sand and Gravel; 1998-02-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → Western Mobile Inc; 1998-02-11 to 2002-01-30; source msha-controller-operator-history
- **operator_operates_mine:** Lafarge West Incorporated → Platte Sand and Gravel; 2002-01-31 to 2011-12-20; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → Platte Sand and Gravel; 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 → Platte Sand and Gravel; 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 → Platte Sand and Gravel; 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