# Relationship history for MSHA mine 2300078

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc. → Columbia East 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 East Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Raid Quarries Division → Columbia East Quarry; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Medusa Corp → Columbia East Quarry; 1950-01-01 to 1979-04-05; source msha-controller-operator-history
- **controller_controls_operator:** Medusa Corp → Raid Quarries Division; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Medusa Corp → Columbia East Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Southdown Inc → Columbia East Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Crane Company → Columbia East Quarry; 1978-12-13 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Medusa Aggregates Company → Columbia East Quarry; 1979-01-01 to 1988-10-06; source msha-controller-operator-history
- **controller_controls_operator:** Crane Company → Medusa Aggregates Company; 1979-01-01 to 1988-10-06; source msha-controller-operator-history
- **operator_operates_mine:** Medusa Aggregates Company → Columbia East Quarry; 1988-10-07 to 1998-06-29; source msha-controller-operator-history
- **controller_controls_operator:** Medusa Corp → Medusa Aggregates Company; 1988-10-07 to 1998-06-29; source msha-controller-operator-history
- **controller_controls_mine:** Cemex S A → Columbia East Quarry; 1994-09-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Southdown Inc → Columbia East Quarry; 1998-06-30 to 2001-02-27; source msha-controller-operator-history
- **controller_controls_operator:** Southdown Inc → Southdown Inc; 1998-06-30 to 2001-02-27; source msha-controller-operator-history
- **operator_operates_mine:** Cemex Inc → Columbia East Quarry; 2001-02-28 to 2001-12-27; source msha-controller-operator-history
- **controller_controls_operator:** Cemex S A → Cemex Inc; 2001-02-28 to 2001-12-27; source msha-controller-operator-history
- **operator_operates_mine:** Con-Agg Companies, LLC → Columbia East Quarry; 2001-12-28 to 2026-03-22; source msha-controller-operator-history
- **controller_controls_mine:** Con-Agg Llc → Columbia East Quarry; 2001-12-28 to 2010-09-14; source msha-controller-operator-history
- **controller_controls_operator:** Con-Agg Llc → Con-Agg Companies, LLC; 2001-12-28 to 2010-09-14; source msha-controller-operator-history
- **controller_controls_mine:** Summit Materials LLC → Columbia East 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 East 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