# Relationship history for MSHA mine 1201997

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials Inc. → Gosport Stone**

- 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 → Gosport Stone; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Crusher Testing Service → Gosport Stone; 1987-03-01 to 2001-05-21; source msha-controller-operator-history
- **controller_controls_mine:** John W  Jones → Gosport Stone; 1987-03-01 to 2001-05-21; source msha-controller-operator-history
- **controller_controls_operator:** John W  Jones → Crusher Testing Service; 1987-03-01 to 2001-05-21; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Aggregates → Gosport Stone; 2001-05-22 to 2005-10-10; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates; 2001-05-22 to 2005-10-10; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials Inc. → Gosport Stone; 2005-10-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials Inc.; 2005-10-11 to current/open; source msha-controller-operator-history