# Relationship history for MSHA mine 4500553

Current hierarchy: **Schaefer John → Twin Rivers Quarry → Twin Rivers 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

- **operator_operates_mine:** Northside Quarry → Twin Rivers Quarry; 1950-01-01 to 1985-10-31; source msha-controller-operator-history
- **controller_controls_mine:** Kent Harold → Twin Rivers Quarry; 1950-01-01 to 1985-10-31; source msha-controller-operator-history
- **controller_controls_operator:** Kent Harold → Northside Quarry; 1950-01-01 to 1985-10-31; source msha-controller-operator-history
- **operator_operates_mine:** D C Rock Company → Twin Rivers Quarry; 1985-11-01 to 1987-02-10; source msha-controller-operator-history
- **controller_controls_mine:** Doug  Connelly → Twin Rivers Quarry; 1985-11-01 to 1987-02-10; source msha-controller-operator-history
- **controller_controls_operator:** Doug  Connelly → D C Rock Company; 1985-11-01 to 1987-02-10; source msha-controller-operator-history
- **operator_operates_mine:** Twin Rivers Quarry Inc → Twin Rivers Quarry; 1987-02-11 to 1989-05-21; source msha-controller-operator-history
- **controller_controls_mine:** Nicholls Chris → Twin Rivers Quarry; 1987-02-11 to 1989-05-21; source msha-controller-operator-history
- **controller_controls_operator:** Nicholls Chris → Twin Rivers Quarry Inc; 1987-02-11 to 1989-05-21; source msha-controller-operator-history
- **operator_operates_mine:** Twin Rivers Quarry → Twin Rivers Quarry; 1989-05-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Schaefer John → Twin Rivers Quarry; 1989-05-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schaefer John → Twin Rivers Quarry; 1989-05-22 to current/open; source msha-controller-operator-history