# Relationship history for MSHA mine 0900716

Current hierarchy: **Quarles Tom → Lawson & Quarles Inc Sand & Gravel → Lawson And Quarles Sand Dredge**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Cherokee Sand & Gravel Inc → Lawson And Quarles Sand Dredge; 1950-01-01 to 1980-02-26; source msha-controller-operator-history
- **controller_controls_mine:** Jenkins James W → Lawson And Quarles Sand Dredge; 1950-01-01 to 1980-02-26; source msha-controller-operator-history
- **controller_controls_operator:** Jenkins James W → Cherokee Sand & Gravel Inc; 1950-01-01 to 1980-02-26; source msha-controller-operator-history
- **operator_operates_mine:** Lawson & Quarles Inc Sand & Gravel → Lawson And Quarles Sand Dredge; 1980-02-27 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Quarles Tom → Lawson And Quarles Sand Dredge; 1980-02-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Quarles Tom → Lawson & Quarles Inc Sand & Gravel; 1980-02-27 to current/open; source msha-controller-operator-history