# Relationship history for MSHA mine 2500815

Current hierarchy: ** → Stalp Gravel Company Inc → Stalp Gravel Company Incorporated**

- 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:** Stalp Gravel Company Inc → Stalp Gravel Company Incorporated; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Henry A  Stalp → Stalp Gravel Company Incorporated; 1950-01-01 to 1989-05-07; source msha-controller-operator-history
- **controller_controls_operator:** Henry A  Stalp → Stalp Gravel Company Inc; 1950-01-01 to 1989-05-07; source msha-controller-operator-history