# Relationship history for MSHA mine 0801031

Current hierarchy: **Vulcan Materials Company → Florida Rock Industries Inc → Tower Sand 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Florida Rock Industries Inc → Tower Sand Plant; 1950-01-01 to 2007-11-15; source msha-controller-operator-history
- **controller_controls_mine:** Jacob B  Dibble et al → Tower Sand Plant; 1950-01-01 to 1990-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Silica Mining Inc → Tower Sand Plant; 1985-06-01 to 1990-07-31; source msha-controller-operator-history
- **controller_controls_operator:** Jacob B  Dibble et al → Silica Mining Inc; 1985-06-01 to 1990-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Florida Rock Industries Inc → Tower Sand Plant; 1990-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Florida Rock Industries Inc → Florida Rock Industries Inc; 1990-08-01 to 2007-11-15; source msha-controller-operator-history
- **controller_controls_mine:** Vulcan Materials Company → Tower Sand Plant; 2007-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vulcan Materials Company → Florida Rock Industries Inc; 2007-11-16 to current/open; source msha-controller-operator-history