# Relationship history for MSHA mine 4604305

Current hierarchy: **Hill Michael J → Z Y Coal Company → Clark Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Z & Y Coal Company Inc → Clark Mine; 1950-01-01 to 1984-05-15; source msha-controller-operator-history
- **controller_controls_mine:** Ray William A → Clark Mine; 1950-01-01 to 1984-05-15; source msha-controller-operator-history
- **controller_controls_operator:** Ray William A → Z & Y Coal Company Inc; 1950-01-01 to 1984-05-15; source msha-controller-operator-history
- **operator_operates_mine:** Z Y Coal Company → Clark Mine; 1984-05-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hill Michael J → Clark Mine; 1984-05-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hill Michael J → Z Y Coal Company; 1984-05-16 to current/open; source msha-controller-operator-history