# Relationship history for MSHA mine 1512688

Current hierarchy: **Stapleton George Douglas → Stapleton Coal Company → Noma Coal Co Prep 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Coal Washing Inc → Noma Coal Co Prep Plant; 1980-12-01 to 1983-06-21; source msha-controller-operator-history
- **controller_controls_mine:** Peterson Roy-Dave Stigler Et Al → Noma Coal Co Prep Plant; 1980-12-01 to 1983-06-21; source msha-controller-operator-history
- **controller_controls_operator:** Peterson Roy-Dave Stigler Et Al → Coal Washing Inc; 1980-12-01 to 1983-06-21; source msha-controller-operator-history
- **operator_operates_mine:** Stapleton Coal Company → Noma Coal Co Prep Plant; 1983-06-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stapleton George Douglas → Noma Coal Co Prep Plant; 1983-06-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stapleton George Douglas → Stapleton Coal Company; 1983-06-22 to current/open; source msha-controller-operator-history