# Relationship history for MSHA mine 4702604

Current hierarchy: **Ewald David → Ewald Sand & Gravel → Ewald 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:** Chet C  Linck → Ewald Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** C C Linck Inc → Ewald Quarry; 1979-01-01 to 1980-05-13; source msha-controller-operator-history
- **controller_controls_operator:** Chet C  Linck → C C Linck Inc; 1979-01-01 to 1980-05-13; source msha-controller-operator-history
- **operator_operates_mine:** Ewald Sand & Gravel → Ewald Quarry; 1980-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ewald David → Ewald Quarry; 1980-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ewald David → Ewald Sand & Gravel; 1980-05-14 to current/open; source msha-controller-operator-history