# Relationship history for MSHA mine 4800977

Current hierarchy: **Core Natural Resources Inc → Thunder Basin Coal Company LLC → Black Thunder**

- 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:** Thunder Basin Coal Company Llc → Black Thunder; 1975-01-01 to 1998-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Atlantic Richfield Company → Black Thunder; 1975-01-01 to 1998-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Atlantic Richfield Company → Thunder Basin Coal Company Llc; 1975-01-01 to 1998-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Thunder Basin Coal Company LLC → Black Thunder; 1998-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc et al → Black Thunder; 1998-06-01 to 2006-02-02; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc et al → Thunder Basin Coal Company LLC; 1998-06-01 to 2006-02-02; source msha-controller-operator-history
- **controller_controls_mine:** Arch Resources Inc → Black Thunder; 2006-02-03 to 2025-01-13; source msha-controller-operator-history
- **controller_controls_operator:** Arch Resources Inc → Thunder Basin Coal Company LLC; 2006-02-03 to 2025-01-13; source msha-controller-operator-history
- **controller_controls_mine:** Core Natural Resources Inc → Black Thunder; 2025-01-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Core Natural Resources Inc → Thunder Basin Coal Company LLC; 2025-01-14 to current/open; source msha-controller-operator-history