# Relationship history for MSHA mine 4503251

Current hierarchy: **John K  Johnson → Dolphin Bay Quarry Inc → Dolphin Bay Quarry**

- 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:** Dolphin Bay Quarry → Dolphin Bay Quarry; 1991-10-01 to 2024-01-31; source msha-controller-operator-history
- **controller_controls_mine:** John K  Johnson → Dolphin Bay Quarry; 1991-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John K  Johnson → Dolphin Bay Quarry; 1991-10-01 to 2024-01-31; source msha-controller-operator-history
- **operator_operates_mine:** Dolphin Bay Quarry Inc → Dolphin Bay Quarry; 2024-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John K  Johnson → Dolphin Bay Quarry; 2024-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John K  Johnson → Dolphin Bay Quarry Inc; 2024-02-01 to current/open; source msha-controller-operator-history