# Relationship history for MSHA mine 2103286

Current hierarchy: **Mark T  Thorson → Mark Sand & Gravel Co. → PLANT 14**

- 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:** Mark T  Thorson → PLANT 14; 1997-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mark T  Thorson → PLANT 14; 2000-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mark Sand & Gravel Acquisition Company → PLANT 14; 2001-04-01 to 2003-09-10; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Thorson → Mark Sand & Gravel Acquisition Company; 2001-04-01 to 2003-09-10; source msha-controller-operator-history
- **operator_operates_mine:** Mark Sand & Gravel Co. → PLANT 14; 2003-09-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Thorson → Mark Sand & Gravel Co.; 2003-09-11 to current/open; source msha-controller-operator-history