# Relationship history for MSHA mine 1800741

Current hierarchy: **William  Schmidt; Gordon  Brown → Bayard Sand & Gravel Llc → BAYARD SAND & GRAVEL LLC**

- 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:** Bayard Sand & Gravel Llc → BAYARD SAND & GRAVEL LLC; 1997-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gordon  Brown  et al → BAYARD SAND & GRAVEL LLC; 1997-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gordon  Brown  et al → Bayard Sand & Gravel Llc; 1997-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William  Schmidt  et al → Bayard Sand & Gravel Llc; 1997-07-01 to current/open; source msha-controller-operator-history