# Relationship history for MSHA mine 4801503

Current hierarchy: **Horizon Natural Resources Incorporated → Wyoming Coal Technology, Inc. → Encoal Plant**

- 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:** Encoal Corp → Encoal Plant; 1991-06-01 to 1992-11-21; source msha-controller-operator-history
- **controller_controls_mine:** Shell Oil Company → Encoal Plant; 1991-06-01 to 1992-11-21; source msha-controller-operator-history
- **controller_controls_operator:** Shell Oil Company → Encoal Corp; 1991-06-01 to 1992-11-21; source msha-controller-operator-history
- **operator_operates_mine:** Encoal Corp → Encoal Plant; 1992-11-22 to 1998-09-01; source msha-controller-operator-history
- **controller_controls_mine:** Zeigler Coal Holding Company → Encoal Plant; 1992-11-22 to 1998-09-01; source msha-controller-operator-history
- **controller_controls_operator:** Zeigler Coal Holding Company → Encoal Corp; 1992-11-22 to 1998-09-01; source msha-controller-operator-history
- **operator_operates_mine:** Wyoming Coal Technology, Inc. → Encoal Plant; 1998-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Horizon Natural Resources Incorporated → Encoal Plant; 1998-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Horizon Natural Resources Incorporated → Wyoming Coal Technology, Inc.; 1998-09-02 to current/open; source msha-controller-operator-history