# Relationship history for MSHA mine 3101636

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc → Alexander Quarry**

- 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 → Alexander Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Emerald Valley Mines → Alexander Quarry; 1950-01-01 to 2000-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Emerald Valley Mines → Alexander Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Emerald Valley Mines → Emerald Valley Mines; 1950-01-01 to 2000-06-30; source msha-controller-operator-history
- **operator_operates_mine:** North American Emerald Mines Inc → Alexander Quarry; 2000-07-01 to 2019-09-03; source msha-controller-operator-history
- **controller_controls_mine:** James K  Hill Jr → Alexander Quarry; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James K  Hill Jr → North American Emerald Mines Inc; 2000-07-01 to 2019-09-03; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc → Alexander Quarry; 2019-09-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials, Inc; 2019-09-04 to current/open; source msha-controller-operator-history