# Relationship history for MSHA mine 3607713

Current hierarchy: **Brown Francis H → B & Y Sand & Gravel Inc → B & Y SAND & GRAVEL INC.**

- 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:** B & Y Sand & Gravel Inc → B & Y SAND & GRAVEL INC.; 1985-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brown Francis H → B & Y SAND & GRAVEL INC.; 1985-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brown Francis H → B & Y Sand & Gravel Inc; 1985-07-01 to current/open; source msha-controller-operator-history