# Relationship history for MSHA mine 1600909

Current hierarchy: **Rials Shelby G → Rials Sand & Gravel → Rials 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Flint Sand & Gravel Company → Rials Pit & Plant; 1950-01-01 to 1978-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Johnson Max L → Rials Pit & Plant; 1950-01-01 to 1978-03-14; source msha-controller-operator-history
- **controller_controls_operator:** Johnson Max L → Flint Sand & Gravel Company; 1950-01-01 to 1978-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Abbott Lowell O → Rials Pit & Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** A L F Sand & Gravel Company → Rials Pit & Plant; 1978-03-15 to 1979-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Abbott Lowell O → A L F Sand & Gravel Company; 1978-03-15 to 1979-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Rials Sand & Gravel → Rials Pit & Plant; 1979-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rials Shelby G → Rials Pit & Plant; 1979-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rials Shelby G → Rials Sand & Gravel; 1979-04-01 to current/open; source msha-controller-operator-history