# Relationship history for MSHA mine 4103212

Current hierarchy: **Brown Gene → Calvert Sand & Gravel Inc → Woodall Pit & Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Brazos Materials Company Inc → Woodall Pit & Plant; 1984-01-01 to 1987-02-11; source msha-controller-operator-history
- **controller_controls_mine:** Graham W K Jr → Woodall Pit & Plant; 1984-01-01 to 1987-02-11; source msha-controller-operator-history
- **controller_controls_operator:** Graham W K Jr → Brazos Materials Company Inc; 1984-01-01 to 1987-02-11; source msha-controller-operator-history
- **operator_operates_mine:** Sandco Inc → Woodall Pit & Plant; 1987-02-12 to 1988-05-18; source msha-controller-operator-history
- **controller_controls_mine:** Assadi Mohammad R → Woodall Pit & Plant; 1987-02-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Assadi Mohammad R → Sandco Inc; 1987-02-12 to 1988-05-18; source msha-controller-operator-history
- **operator_operates_mine:** Calvert Sand & Gravel Inc → Woodall Pit & Plant; 1988-05-19 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brown Gene → Woodall Pit & Plant; 1988-05-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brown Gene → Calvert Sand & Gravel Inc; 1988-05-19 to current/open; source msha-controller-operator-history