# Relationship history for MSHA mine 4103366

Current hierarchy: **Donald L  Poarch; Joseph B  Swinbank → Sprint Sand & Gravel Company → Ferris Pit & Plant**

- 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

- **controller_controls_mine:** Donald L  Poarch et al → Ferris Pit & Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sprint Sand & Gravel Company → Ferris Pit & Plant; 1986-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald L  Poarch et al → Sprint Sand & Gravel Company; 1986-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Joseph B  Swinbank et al → Sprint Sand & Gravel Company; 1986-01-01 to current/open; source msha-controller-operator-history