# Relationship history for MSHA mine 2000657

Current hierarchy: **Daniel R  Balkema; Ralph T  Balkema → Balkema Excavating Inc → TOMAHAWK**

- 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:** Aggregate Processors Inc → TOMAHAWK; 1950-01-01 to 1993-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Aldrich Ronald D → TOMAHAWK; 1950-01-01 to 1993-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Aldrich Ronald D → Aggregate Processors Inc; 1950-01-01 to 1993-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Daniel R  Balkema et al → TOMAHAWK; 1989-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Morris Sand & Gravel Inc → TOMAHAWK; 1993-10-01 to 1997-06-15; source msha-controller-operator-history
- **controller_controls_mine:** Morris Thomas S → TOMAHAWK; 1993-10-01 to 1997-06-15; source msha-controller-operator-history
- **controller_controls_operator:** Morris Thomas S → Morris Sand & Gravel Inc; 1993-10-01 to 1997-06-15; source msha-controller-operator-history
- **operator_operates_mine:** Balkema Excavating Inc → TOMAHAWK; 1997-06-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Daniel R  Balkema et al → Balkema Excavating Inc; 1997-06-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ralph T  Balkema et al → Balkema Excavating Inc; 1997-06-16 to current/open; source msha-controller-operator-history