# Relationship history for MSHA mine 2101419

Current hierarchy: **Mark T  Thorson → Mark Sand & Gravel Co. → Plant 5**

- 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:** Donald C  Ashworth → Plant 5; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mark Sand & Gravel Company → Plant 5; 1988-07-01 to 2002-03-10; source msha-controller-operator-history
- **controller_controls_operator:** Donald C  Ashworth → Mark Sand & Gravel Company; 1988-07-01 to 2002-03-10; source msha-controller-operator-history
- **controller_controls_mine:** Mark T  Thorson → Plant 5; 1997-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mark Sand & Gravel Co. → Plant 5; 2002-03-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Thorson → Mark Sand & Gravel Co.; 2002-03-11 to current/open; source msha-controller-operator-history