# Relationship history for MSHA mine 0301520

Current hierarchy: **Walker Michael W → Aearth Preparation Inc → Aearth Preparation Inc Site #1**

- 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:** Aearth Preparation Inc → Aearth Preparation Inc Site #1; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Walker Michael W → Aearth Preparation Inc Site #1; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Walker Michael W → Aearth Preparation Inc; 1981-09-01 to current/open; source msha-controller-operator-history