# Relationship history for MSHA mine 3304011

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials Inc. → Shamrock Sand & 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Martin Marietta Materials Inc → Shamrock Sand & Gravel; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Martin Farms Inc → Shamrock Sand & Gravel; 1985-04-01 to 1990-02-05; source msha-controller-operator-history
- **controller_controls_mine:** James  Martin → Shamrock Sand & Gravel; 1985-04-01 to 1990-02-05; source msha-controller-operator-history
- **controller_controls_operator:** James  Martin → Martin Farms Inc; 1985-04-01 to 1990-02-05; source msha-controller-operator-history
- **operator_operates_mine:** Shamrock Gravel Company Inc → Shamrock Sand & Gravel; 1990-02-06 to 1993-02-11; source msha-controller-operator-history
- **controller_controls_mine:** Don M  Clise → Shamrock Sand & Gravel; 1990-02-06 to 1993-02-11; source msha-controller-operator-history
- **controller_controls_operator:** Don M  Clise → Shamrock Gravel Company Inc; 1990-02-06 to 1993-02-11; source msha-controller-operator-history
- **operator_operates_mine:** Shamrock Materials Inc. → Shamrock Sand & Gravel; 1993-02-12 to 2015-02-01; source msha-controller-operator-history
- **controller_controls_mine:** James P  Jurgensen → Shamrock Sand & Gravel; 1993-02-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James P  Jurgensen → Shamrock Materials Inc.; 1993-02-12 to 2015-02-01; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials Inc. → Shamrock Sand & Gravel; 2015-02-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials Inc.; 2015-02-02 to current/open; source msha-controller-operator-history