# Relationship history for MSHA mine 1301225

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc. → Durham Mine & 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Martin Marietta Materials Inc → Durham Mine & Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Kaser Corp → Durham Mine & Mill; 1950-01-01 to 1997-09-04; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc et al → Durham Mine & Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc et al → Kaser Corp; 1950-01-01 to 1997-09-04; source msha-controller-operator-history
- **controller_controls_operator:** Kaser Corporation et al → Kaser Corp; 1950-01-01 to 1997-09-04; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Aggregates Of Southern Iowa Inc → Durham Mine & Mill; 1997-09-05 to 2006-07-12; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Durham Mine & Mill; 1997-09-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates Of Southern Iowa Inc; 1997-09-05 to 2006-07-12; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc. → Durham Mine & Mill; 2006-07-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials, Inc.; 2006-07-13 to current/open; source msha-controller-operator-history