# Relationship history for MSHA mine 4102252

Current hierarchy: **Ford John D → Ford Sand & Gravel → Ford Pit And Plant**

- 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:** Ford Sand & Gravel → Ford Pit And Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ford John D → Ford Pit And Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ford John D → Ford Sand & Gravel; 1950-01-01 to current/open; source msha-controller-operator-history