# Relationship history for MSHA mine 0503510

Current hierarchy: **CRH PLC → Oldcastle SW Group, Inc. → Portable Wash Plant (WP #4)**

- 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

- **controller_controls_mine:** Richard  Tibbits  et al → Portable Wash Plant (WP #4); 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Nielsons Holding Company → Portable Wash Plant (WP #4); 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Nielsons Inc → Portable Wash Plant (WP #4); 1981-04-01 to 1984-05-22; source msha-controller-operator-history
- **controller_controls_operator:** Nielsons Holding Company → Nielsons Inc; 1981-04-01 to 1984-05-22; source msha-controller-operator-history
- **operator_operates_mine:** Mountain Gravel & Construction Company → Portable Wash Plant (WP #4); 1984-05-23 to 1998-06-07; source msha-controller-operator-history
- **controller_controls_operator:** Richard  Tibbits  et al → Mountain Gravel & Construction Company; 1984-05-23 to 1998-06-07; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Portable Wash Plant (WP #4); 1998-01-05 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Oldcastle SW Group, Inc. → Portable Wash Plant (WP #4); 1998-06-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Oldcastle SW Group, Inc.; 1998-06-08 to current/open; source msha-controller-operator-history