# Relationship history for MSHA mine 3600186

Current hierarchy: **Heidelberg Materials AG → Lehigh Cement Company LLC → Oley No 1 Quarry**

- 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:** National Gypsum Company → Oley No 1 Quarry; 1950-01-01 to 2002-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Lafarge S A → Oley No 1 Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lafarge S A → National Gypsum Company; 1950-01-01 to 2002-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → Oley No 1 Quarry; 2000-07-21 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Lehigh Cement Company LLC → Oley No 1 Quarry; 2002-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Lehigh Cement Company LLC; 2002-02-01 to current/open; source msha-controller-operator-history