# Relationship history for MSHA mine 4003373

Current hierarchy: **Tommy  Shannon; Alan  Sjoberg → Hard Rock Sand and Gravel → Hard Rock Sand and Gravel**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Hard Rock Sand and Gravel → Hard Rock Sand and Gravel; 2010-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tommy  Shannon et al → Hard Rock Sand and Gravel; 2010-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tommy  Shannon et al → Hard Rock Sand and Gravel; 2010-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alan  Sjoberg et al → Hard Rock Sand and Gravel; 2010-03-01 to current/open; source msha-controller-operator-history