# Relationship history for MSHA mine 1700926

Current hierarchy: **Dedra M  Chick; Michael W  Chick → MainEx → MainEx Windsor Gravel 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** MainEx → MainEx Windsor Gravel Pit; 2014-04-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael W  Chick et al → MainEx Windsor Gravel Pit; 2014-04-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael W  Chick et al → MainEx; 2014-04-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dedra M  Chick et al → MainEx; 2014-04-22 to current/open; source msha-controller-operator-history