# Relationship history for MSHA mine 4300833

Current hierarchy: **Chris  Acker → Acker Sand and Gravel → Bolton 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:** Alan  Clark et al → Bolton Pit; 2000-09-01 to 2017-12-30; source msha-controller-operator-history
- **controller_controls_mine:** Chris  Acker → Bolton Pit; 2017-12-31 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Acker Sand and Gravel → Bolton Pit; 2025-08-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chris  Acker → Acker Sand and Gravel; 2025-08-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alan  Clark et al → Acker Sand and Gravel; 2025-08-11 to 2017-12-30; source msha-controller-operator-history
- **controller_controls_operator:** Chris  Acker et al → Acker Sand and Gravel; 2025-08-11 to 2017-12-30; source msha-controller-operator-history