# Relationship history for MSHA mine 2000379

Current hierarchy: **Thomas D  Webber → Michigan Gypsum Company → Michigan Gypsum Pit & Mill**

- 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:** Michigan Gypsum Company → Michigan Gypsum Pit & Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Francesanna  Sargent → Michigan Gypsum Pit & Mill; 1950-01-01 to 2014-04-10; source msha-controller-operator-history
- **controller_controls_operator:** Francesanna  Sargent → Michigan Gypsum Company; 1950-01-01 to 2014-04-10; source msha-controller-operator-history
- **controller_controls_mine:** Thomas D  Webber → Michigan Gypsum Pit & Mill; 2014-04-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomas D  Webber → Michigan Gypsum Company; 2014-04-11 to current/open; source msha-controller-operator-history