# Relationship history for MSHA mine 2101929

Current hierarchy: **Martin Marietta Materials Inc → Barton Sand & Gravel → 769 Quarry And Mill**

- 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

- **operator_operates_mine:** Barton Contracting Company → 769 Quarry And Mill; 1950-01-01 to 1983-02-28; source msha-controller-operator-history
- **controller_controls_mine:** Eugene  Barton → 769 Quarry And Mill; 1950-01-01 to 1983-02-28; source msha-controller-operator-history
- **controller_controls_operator:** Eugene  Barton → Barton Contracting Company; 1950-01-01 to 1983-02-28; source msha-controller-operator-history
- **operator_operates_mine:** Barton Sand & Gravel → 769 Quarry And Mill; 1983-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tiller Corp → 769 Quarry And Mill; 1983-03-01 to 2021-05-03; source msha-controller-operator-history
- **controller_controls_operator:** Tiller Corp → Barton Sand & Gravel; 1983-03-01 to 2021-05-03; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → 769 Quarry And Mill; 2021-05-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Barton Sand & Gravel; 2021-05-04 to current/open; source msha-controller-operator-history