# Relationship history for MSHA mine 1800561

Current hierarchy: **Morris Guy E Jr → Ponderosa Coal Company Inc → Ponderosa No 1 Strip**

- 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:** Ponderosa Coal Company → Ponderosa No 1 Strip; 1950-01-01 to 1975-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Lawson Marlin R → Ponderosa No 1 Strip; 1950-01-01 to 1975-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Lawson Marlin R → Ponderosa Coal Company; 1950-01-01 to 1975-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Ponderosa Coal Company Inc → Ponderosa No 1 Strip; 1975-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Morris Guy E Jr → Ponderosa No 1 Strip; 1975-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Morris Guy E Jr → Ponderosa Coal Company Inc; 1975-10-01 to current/open; source msha-controller-operator-history