# Relationship history for MSHA mine 3800378

Current hierarchy: **T M  Hoefer; H W  Hoefer → Columbia Silica Sand Inc → Shuler Mine And Mill**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Columbia Silica Sand Inc → Shuler Mine And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** T M  Hoefer  et al → Shuler Mine And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** T M  Hoefer  et al → Columbia Silica Sand Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** H W  Hoefer  et al → Columbia Silica Sand Inc; 1950-01-01 to current/open; source msha-controller-operator-history