# Relationship history for MSHA mine 4609205

Current hierarchy: **Alpha Natural Resources, Inc. → Progress Coal Company → No. 1 High Wall Miner**

- 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

- **controller_controls_mine:** Massey Energy Company → No. 1 High Wall Miner; 1997-06-01 to 2011-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Progress Coal Company → No. 1 High Wall Miner; 2007-03-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Massey Energy Company → Progress Coal Company; 2007-03-29 to 2011-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Alpha Natural Resources, Inc. → No. 1 High Wall Miner; 2011-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alpha Natural Resources, Inc. → Progress Coal Company; 2011-06-01 to current/open; source msha-controller-operator-history