# Relationship history for MSHA mine 1600467

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Aggregates → DREDGE MALLARD**

- 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 → DREDGE MALLARD; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Radcliff Materials Inc → DREDGE MALLARD; 1950-01-01 to 1979-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Southern Industries Inc → DREDGE MALLARD; 1950-01-01 to 1979-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Southern Industries Inc → Radcliff Materials Inc; 1950-01-01 to 1979-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Dravo Corp → DREDGE MALLARD; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Dravo Basic Materials Company Inc → DREDGE MALLARD; 1979-06-01 to 1992-12-24; source msha-controller-operator-history
- **controller_controls_operator:** Dravo Corp → Dravo Basic Materials Company Inc; 1979-06-01 to 1992-12-24; source msha-controller-operator-history
- **controller_controls_mine:** St Charles Dredging Corp Et Al → DREDGE MALLARD; 1991-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Louisiana Dredging Company → DREDGE MALLARD; 1992-12-25 to 1995-01-02; source msha-controller-operator-history
- **controller_controls_operator:** St Charles Dredging Corp Et Al → Louisiana Dredging Company; 1992-12-25 to 1995-01-02; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Aggregates → DREDGE MALLARD; 1995-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates; 1995-01-03 to current/open; source msha-controller-operator-history