# Relationship history for MSHA mine 3502759

Current hierarchy: **Clark Frank → Oregon Rock Products Inc → Oregon Rock Products Incorporated**

- 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

- **operator_operates_mine:** Dale'S Sand & Gravel Company Inc → Oregon Rock Products Incorporated; 1950-01-01 to 1981-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Yocum Cecil J → Oregon Rock Products Incorporated; 1950-01-01 to 1981-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Yocum Cecil J → Dale'S Sand & Gravel Company Inc; 1950-01-01 to 1981-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Tonquin Quarry Company → Oregon Rock Products Incorporated; 1981-06-01 to 1983-03-23; source msha-controller-operator-history
- **controller_controls_mine:** Kalkhoven Al → Oregon Rock Products Incorporated; 1981-06-01 to 1983-03-23; source msha-controller-operator-history
- **controller_controls_operator:** Kalkhoven Al → Tonquin Quarry Company; 1981-06-01 to 1983-03-23; source msha-controller-operator-history
- **operator_operates_mine:** Oregon Rock Products Inc → Oregon Rock Products Incorporated; 1983-03-24 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Clark Frank → Oregon Rock Products Incorporated; 1983-03-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Clark Frank → Oregon Rock Products Inc; 1983-03-24 to current/open; source msha-controller-operator-history