# Relationship history for MSHA mine 0501914

Current hierarchy: **Redland Plc → Western Mobile/Mtn → Screen Plant #19030**

- 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

- **controller_controls_mine:** M P M Inc → Screen Plant #19030; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Zemlock & Son Inc → Screen Plant #19030; 1950-01-01 to 1984-05-22; source msha-controller-operator-history
- **controller_controls_mine:** Zemlock Martin S → Screen Plant #19030; 1950-01-01 to 1984-05-22; source msha-controller-operator-history
- **controller_controls_operator:** Zemlock Martin S → Zemlock & Son Inc; 1950-01-01 to 1984-05-22; source msha-controller-operator-history
- **operator_operates_mine:** Mobile Premix Company → Screen Plant #19030; 1984-05-23 to 1987-05-20; source msha-controller-operator-history
- **controller_controls_operator:** M P M Inc → Mobile Premix Company; 1984-05-23 to 1987-05-20; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Co Inc & Redland Plc → Screen Plant #19030; 1987-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mobile Premix Company → Screen Plant #19030; 1987-05-21 to 1988-06-13; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Co Inc & Redland Plc → Mobile Premix Company; 1987-05-21 to 1988-06-13; source msha-controller-operator-history
- **operator_operates_mine:** Western Mobile/Mtn → Screen Plant #19030; 1988-06-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Redland Plc → Screen Plant #19030; 1988-06-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Redland Plc → Western Mobile/Mtn; 1988-06-14 to current/open; source msha-controller-operator-history