# Relationship history for MSHA mine 4201459

Current hierarchy: **Ence Jay → Ence Sand & Gravel → Ence Sand & Gravel (Portable)**

- 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

- **operator_operates_mine:** Parry Sand & Gravel Company → Ence Sand & Gravel (Portable); 1950-01-01 to 1993-08-09; source msha-controller-operator-history
- **controller_controls_mine:** Parry Sherwin L → Ence Sand & Gravel (Portable); 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Parry Sherwin L → Parry Sand & Gravel Company; 1950-01-01 to 1993-08-09; source msha-controller-operator-history
- **operator_operates_mine:** Ence Sand & Gravel → Ence Sand & Gravel (Portable); 1993-08-10 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ence Jay → Ence Sand & Gravel (Portable); 1993-08-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ence Jay → Ence Sand & Gravel; 1993-08-10 to current/open; source msha-controller-operator-history