# Relationship history for MSHA mine 2002904

Current hierarchy: **Ronald A  Stevick → Stevick Gravel Inc → Hart Pit**

- 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:** Ronald A  Stevick → Hart Pit; 1979-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Stevick Gravel Inc → Hart Pit; 1993-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ronald A  Stevick → Stevick Gravel Inc; 1993-06-01 to current/open; source msha-controller-operator-history