# Relationship history for MSHA mine 0202972

Current hierarchy: **Ben  Overson → Thunderbird Materials LLC → Sawmill Wash 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

- **operator_operates_mine:** Thunderbird Materials LLC → Sawmill Wash Pit; 2002-04-11 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Blake  Schritter → Sawmill Wash Pit; 2002-04-11 to 2004-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Blake  Schritter → Thunderbird Materials LLC; 2002-04-11 to 2004-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Ben  Overson → Sawmill Wash Pit; 2004-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ben  Overson → Thunderbird Materials LLC; 2004-06-01 to current/open; source msha-controller-operator-history