# Relationship history for MSHA mine 4407237

Current hierarchy: **Alpha Natural Resources, Inc. → Bluff Spur Coal Corporation → Marker Portal 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

- **controller_controls_mine:** Cumberland Resources Corporation → Marker Portal Mine; 2000-03-10 to 2010-04-18; source msha-controller-operator-history
- **operator_operates_mine:** Bluff Spur Coal Corporation → Marker Portal Mine; 2008-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cumberland Resources Corporation → Bluff Spur Coal Corporation; 2008-10-01 to 2010-04-18; source msha-controller-operator-history
- **controller_controls_mine:** Massey Energy Company → Marker Portal Mine; 2010-04-19 to 2011-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Massey Energy Company → Bluff Spur Coal Corporation; 2010-04-19 to 2011-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Alpha Natural Resources, Inc. → Marker Portal Mine; 2011-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alpha Natural Resources, Inc. → Bluff Spur Coal Corporation; 2011-06-01 to current/open; source msha-controller-operator-history