# Relationship history for MSHA mine 4104680

Current hierarchy: **Becky Dean  Walker; Dennis  Walker → Sierra Blanca Quarry, LLC → Sierra Blanca Quarry**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Sierra Blanca Quarry, LLC → Sierra Blanca Quarry; 2007-08-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert  Albritton → Sierra Blanca Quarry; 2007-08-15 to 2009-07-31; source msha-controller-operator-history
- **controller_controls_operator:** Robert  Albritton → Sierra Blanca Quarry, LLC; 2007-08-15 to 2009-07-31; source msha-controller-operator-history
- **controller_controls_mine:** Dennis  Walker et al → Sierra Blanca Quarry; 2009-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dennis  Walker et al → Sierra Blanca Quarry, LLC; 2009-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Becky Dean  Walker et al → Sierra Blanca Quarry, LLC; 2009-08-01 to current/open; source msha-controller-operator-history