# Relationship history for MSHA mine 2301894

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc. → Columbia North 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Martin Marietta Materials Inc → Columbia North Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Eric S  Strope et al → Columbia North Quarry; 1984-03-21 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Beck Materials Company → Columbia North Quarry; 1984-05-01 to 1995-10-30; source msha-controller-operator-history
- **controller_controls_operator:** Eric S  Strope et al → Beck Materials Company; 1984-05-01 to 1995-10-30; source msha-controller-operator-history
- **operator_operates_mine:** Central Quarries & Materials Company Llc → Columbia North Quarry; 1995-10-31 to 1998-02-02; source msha-controller-operator-history
- **controller_controls_mine:** William D  Eckhoff et al → Columbia North Quarry; 1995-10-31 to 1998-02-02; source msha-controller-operator-history
- **controller_controls_operator:** William D  Eckhoff et al → Central Quarries & Materials Company Llc; 1995-10-31 to 1998-02-02; source msha-controller-operator-history
- **operator_operates_mine:** Apac-Missouri Inc → Columbia North Quarry; 1998-02-03 to 2003-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc → Columbia North Quarry; 1998-02-03 to 2006-08-27; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc → Apac-Missouri Inc; 1998-02-03 to 2003-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Con-Agg Llc → Columbia North Quarry; 2001-12-28 to 2010-09-14; source msha-controller-operator-history
- **operator_operates_mine:** Con-Agg Companies, LLC → Columbia North Quarry; 2003-04-01 to 2026-03-22; source msha-controller-operator-history
- **controller_controls_operator:** Con-Agg Llc → Con-Agg Companies, LLC; 2003-04-01 to 2010-09-14; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Columbia North Quarry; 2006-08-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Apac-Missouri Inc; 2006-08-28 to 2003-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Summit Materials LLC → Columbia North Quarry; 2010-09-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Summit Materials LLC → Con-Agg Companies, LLC; 2010-09-15 to 2026-03-22; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc. → Columbia North Quarry; 2026-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials, Inc.; 2026-03-23 to current/open; source msha-controller-operator-history