# Relationship history for MSHA mine 1101093

Current hierarchy: **Robert V  Nolan → Duck Island Sand & Gravel Company → DUCK ISLAND SAND & GRAVEL CO.**

- 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:** Liverpool Materials Company → DUCK ISLAND SAND & GRAVEL CO.; 1950-01-01 to 1981-08-02; source msha-controller-operator-history
- **controller_controls_mine:** Lelia M  Linn → DUCK ISLAND SAND & GRAVEL CO.; 1950-01-01 to 1981-08-02; source msha-controller-operator-history
- **controller_controls_operator:** Lelia M  Linn → Liverpool Materials Company; 1950-01-01 to 1981-08-02; source msha-controller-operator-history
- **operator_operates_mine:** Duck Island Sand & Gravel Company → DUCK ISLAND SAND & GRAVEL CO.; 1981-08-03 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert V  Nolan → DUCK ISLAND SAND & GRAVEL CO.; 1981-08-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert V  Nolan → Duck Island Sand & Gravel Company; 1981-08-03 to current/open; source msha-controller-operator-history