# Relationship history for MSHA mine 1101187

Current hierarchy: **Oberlaender Donald & Darrell Woodbury → Oberlaender Sand Company → Oberlaender Sand Company**

- 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:** Colona Sand & Excavating Inc → Oberlaender Sand Company; 1984-03-01 to 1987-06-02; source msha-controller-operator-history
- **controller_controls_mine:** Beverly J  Ropp → Oberlaender Sand Company; 1984-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Beverly J  Ropp → Colona Sand & Excavating Inc; 1984-03-01 to 1987-06-02; source msha-controller-operator-history
- **operator_operates_mine:** Oberlaender Sand Company → Oberlaender Sand Company; 1987-06-03 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Oberlaender Donald & Darrell Woodbury → Oberlaender Sand Company; 1987-06-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Oberlaender Donald & Darrell Woodbury → Oberlaender Sand Company; 1987-06-03 to current/open; source msha-controller-operator-history