# Relationship history for MSHA mine 0401616

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Northern California Aggregates,LLC → Santa Margarita Aggregates**

- 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:** Koppers Company Inc → Santa Margarita Aggregates; 1950-01-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Santa Margarita Aggregates; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Kaiser Sand & Gravel Company → Santa Margarita Aggregates; 1978-01-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Company Inc → Kaiser Sand & Gravel Company; 1978-01-01 to 1988-11-13; source msha-controller-operator-history
- **operator_operates_mine:** Hanson Aggregates West Inc → Santa Margarita Aggregates; 1988-11-14 to 2006-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hanson Aggregates West Inc; 1988-11-14 to 2006-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Santa Margarita Aggregates; 2005-09-15 to 2007-08-22; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Northern California Aggregates,LLC → Santa Margarita Aggregates; 2006-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Martin Marietta Northern California Aggregates,LLC; 2006-06-01 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → Santa Margarita Aggregates; 2007-08-23 to 2021-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Martin Marietta Northern California Aggregates,LLC; 2007-08-23 to 2021-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Santa Margarita Aggregates; 2021-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Northern California Aggregates,LLC; 2021-10-01 to current/open; source msha-controller-operator-history