# Relationship history for MSHA mine 4000021

Current hierarchy: **Rogers Group Inc → Rogers Group Inc → Cowan 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:** Rogers Group Inc → Cowan Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Cowan Stone Company → Cowan Quarry; 1950-01-01 to 1989-09-15; source msha-controller-operator-history
- **controller_controls_mine:** Cowan Stone Company → Cowan Quarry; 1950-01-01 to 1989-09-15; source msha-controller-operator-history
- **controller_controls_operator:** Cowan Stone Company → Cowan Stone Company; 1950-01-01 to 1989-09-15; source msha-controller-operator-history
- **operator_operates_mine:** Crushed Stone Inc → Cowan Quarry; 1989-09-16 to 1991-12-18; source msha-controller-operator-history
- **controller_controls_mine:** Leonard T  Lewis → Cowan Quarry; 1989-09-16 to 1991-12-18; source msha-controller-operator-history
- **controller_controls_operator:** Leonard T  Lewis → Crushed Stone Inc; 1989-09-16 to 1991-12-18; source msha-controller-operator-history
- **operator_operates_mine:** Rogers Group Inc → Cowan Quarry; 1991-12-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rogers Group Inc → Rogers Group Inc; 1991-12-19 to current/open; source msha-controller-operator-history