# Relationship history for MSHA mine 2102479

Current hierarchy: **Vernon  Troumbly → B T C Inc → Crusher**

- 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; 1950-01-01 to 1989-08-16; source msha-controller-operator-history
- **controller_controls_mine:** W T  Thorson → Crusher; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W T  Thorson → Thorson Inc; 1950-01-01 to 1989-08-16; source msha-controller-operator-history
- **operator_operates_mine:** B T C Inc → Crusher; 1989-08-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Vernon  Troumbly  et al → Crusher; 1989-08-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vernon  Troumbly  et al → B T C Inc; 1989-08-17 to current/open; source msha-controller-operator-history