# Relationship history for MSHA mine 3200805

Current hierarchy: **Mark T  Thorson → Mark Sand & Gravel Dakota Co → Portable Crusher -101**

- 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:** Mark Sand & Gravel Dakota Co → Portable Crusher -101; 2002-09-11 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mark T  Thorson → Portable Crusher -101; 2002-09-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Thorson → Mark Sand & Gravel Dakota Co; 2002-09-11 to current/open; source msha-controller-operator-history