# Relationship history for MSHA mine 2501026

Current hierarchy: **Timothy L  Stalp → Nebraska Sand & Gravel Inc → Nebraska 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Timothy L  Stalp → Nebraska Sand & Gravel Inc.; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Nebraska Sand & Gravel Inc → Nebraska Sand & Gravel Inc.; 1984-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Timothy L  Stalp → Nebraska Sand & Gravel Inc; 1984-10-01 to current/open; source msha-controller-operator-history