# Relationship history for MSHA mine 1516323

Current hierarchy: **Pickens Dennis K → Waste Coal Management Inc → Black Mountain**

- 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:** Sumco Inc → Black Mountain; 1988-03-01 to 1989-02-15; source msha-controller-operator-history
- **controller_controls_mine:** Summers R E → Black Mountain; 1988-03-01 to 1989-02-15; source msha-controller-operator-history
- **controller_controls_operator:** Summers R E → Sumco Inc; 1988-03-01 to 1989-02-15; source msha-controller-operator-history
- **operator_operates_mine:** Ri-Jon → Black Mountain; 1989-02-16 to 1990-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Johnson Robert & Wayne Riley → Black Mountain; 1989-02-16 to 1990-01-31; source msha-controller-operator-history
- **controller_controls_operator:** Johnson Robert & Wayne Riley → Ri-Jon; 1989-02-16 to 1990-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Pickens Dennis K Et Al → Black Mountain; 1990-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Waste Coal Management Inc → Black Mountain; 1990-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Pickens Dennis K Et Al → Waste Coal Management Inc; 1990-02-01 to current/open; source msha-controller-operator-history