# Relationship history for MSHA mine 2501231

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc. → West Center Sand**

- 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 → West Center Sand; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Don  Rogert → West Center Sand; 1993-08-13 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mallard Sand & Gravel Co. → West Center Sand; 2007-03-22 to 2008-12-03; source msha-controller-operator-history
- **controller_controls_operator:** Don  Rogert → Mallard Sand & Gravel Co.; 2007-03-22 to 2008-12-03; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → West Center Sand; 2008-01-03 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mallard Sand and Gravel → West Center Sand; 2008-12-04 to 2018-06-22; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Mallard Sand and Gravel; 2008-12-04 to 2018-06-22; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc. → West Center Sand; 2018-06-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials, Inc.; 2018-06-23 to current/open; source msha-controller-operator-history