# Relationship history for MSHA mine 1601252

Current hierarchy: **George  Douglass Jr → Pontchartrain Materials Corp → SAND 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

- **operator_operates_mine:** Pontchartrain Materials Corp → SAND PLANT; 1992-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** George  Douglass Jr → SAND PLANT; 1992-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** George  Douglass Jr → Pontchartrain Materials Corp; 1992-12-01 to current/open; source msha-controller-operator-history