# Relationship history for MSHA mine 4500653

Current hierarchy: **Jane A  Hallock → Central Whidbey Sand & Gravel → Central Whidbey Sand & Gravel**

- 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:** Libbey Concrete & Materials Inc → Central Whidbey Sand & Gravel; 1950-01-01 to 1981-11-30; source msha-controller-operator-history
- **controller_controls_mine:** Shelton Mike & William B Engle → Central Whidbey Sand & Gravel; 1950-01-01 to 1985-01-07; source msha-controller-operator-history
- **controller_controls_operator:** Shelton Mike & William B Engle → Libbey Concrete & Materials Inc; 1950-01-01 to 1981-11-30; source msha-controller-operator-history
- **operator_operates_mine:** Island Sand & Gravel → Central Whidbey Sand & Gravel; 1981-12-01 to 1983-03-01; source msha-controller-operator-history
- **controller_controls_mine:** Iverson Keith → Central Whidbey Sand & Gravel; 1981-12-01 to 1983-03-01; source msha-controller-operator-history
- **controller_controls_operator:** Iverson Keith → Island Sand & Gravel; 1981-12-01 to 1983-03-01; source msha-controller-operator-history
- **operator_operates_mine:** Libbey Concrete & Materials Inc → Central Whidbey Sand & Gravel; 1983-03-02 to 1985-01-07; source msha-controller-operator-history
- **controller_controls_operator:** Shelton Mike & William B Engle → Libbey Concrete & Materials Inc; 1983-03-02 to 1985-01-07; source msha-controller-operator-history
- **operator_operates_mine:** Central Whidbey Sand & Gravel → Central Whidbey Sand & Gravel; 1985-01-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Jane A  Hallock → Central Whidbey Sand & Gravel; 1985-01-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jane A  Hallock → Central Whidbey Sand & Gravel; 1985-01-08 to current/open; source msha-controller-operator-history