# Relationship history for MSHA mine 2300951

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc. → Big Springs 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 → Big Springs Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Big Spring Quarries → Big Springs Quarry; 1950-01-01 to 1981-08-30; source msha-controller-operator-history
- **controller_controls_mine:** William  Staggenborg → Big Springs Quarry; 1950-01-01 to 1981-08-30; source msha-controller-operator-history
- **controller_controls_operator:** William  Staggenborg → Big Spring Quarries; 1950-01-01 to 1981-08-30; source msha-controller-operator-history
- **controller_controls_mine:** Mertens Construction Company Inc → Big Springs Quarry; 1981-05-26 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mid-Missouri Limestone, Inc → Big Springs Quarry; 1981-08-31 to 2018-01-25; source msha-controller-operator-history
- **controller_controls_operator:** Mertens Construction Company Inc → Mid-Missouri Limestone, Inc; 1981-08-31 to 2018-01-25; source msha-controller-operator-history
- **controller_controls_mine:** Con-Agg Llc → Big Springs Quarry; 2001-12-28 to 2010-09-14; source msha-controller-operator-history
- **controller_controls_mine:** Summit Materials LLC → Big Springs Quarry; 2010-09-15 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Con-Agg Companies, LLC → Big Springs Quarry; 2018-01-26 to 2026-03-22; source msha-controller-operator-history
- **controller_controls_operator:** Con-Agg Llc → Con-Agg Companies, LLC; 2018-01-26 to 2010-09-14; source msha-controller-operator-history
- **controller_controls_operator:** Summit Materials LLC → Con-Agg Companies, LLC; 2018-01-26 to 2026-03-22; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc. → Big Springs 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