# Relationship history for MSHA mine 2100645

Current hierarchy: **Mark T  Thorson → Mark Sand & Gravel Acquisition Company → CRUSHER PLANT 3**

- 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

- **operator_operates_mine:** Thorson Inc → CRUSHER PLANT 3; 1950-01-01 to 1999-12-31; source msha-controller-operator-history
- **controller_controls_mine:** W T  Thorson → CRUSHER PLANT 3; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W T  Thorson → Thorson Inc; 1950-01-01 to 1999-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Mark Sand & Gravel Acquisition Company → CRUSHER PLANT 3; 2000-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mark T  Thorson → CRUSHER PLANT 3; 2000-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Thorson → Mark Sand & Gravel Acquisition Company; 2000-01-01 to current/open; source msha-controller-operator-history