# Relationship history for MSHA mine 0504635

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials Inc. → Parkdale 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 → Parkdale Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Agile Stone Systems Inc → Parkdale Quarry; 1999-01-01 to 2004-07-18; source msha-controller-operator-history
- **controller_controls_mine:** Mitch  Albert  et al → Parkdale Quarry; 1999-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mitch  Albert  et al → Agile Stone Systems Inc; 1999-01-01 to 2004-07-18; source msha-controller-operator-history
- **controller_controls_operator:** Bill  Fehr  et al → Agile Stone Systems Inc; 1999-01-01 to 2004-07-18; source msha-controller-operator-history
- **operator_operates_mine:** Front Range Aggregates, LLC → Parkdale Quarry; 2004-07-19 to 2015-12-02; source msha-controller-operator-history
- **controller_controls_mine:** CIG LLC → Parkdale Quarry; 2004-07-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CIG LLC → Front Range Aggregates, LLC; 2004-07-19 to 2015-12-02; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials Inc. → Parkdale Quarry; 2015-12-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials Inc.; 2015-12-03 to current/open; source msha-controller-operator-history