# Relationship history for MSHA mine 4702590

Current hierarchy: **Frostman Ralph A → South Shore Sand & Gravel → O'BRION PIT**

- 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:** R Frostman Inc → O'BRION PIT; 1979-01-01 to 1980-05-25; source msha-controller-operator-history
- **controller_controls_mine:** Frostman Ray → O'BRION PIT; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frostman Ray → R Frostman Inc; 1979-01-01 to 1980-05-25; source msha-controller-operator-history
- **operator_operates_mine:** South Shore Sand & Gravel → O'BRION PIT; 1980-05-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Frostman Ralph A → O'BRION PIT; 1980-05-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frostman Ralph A → South Shore Sand & Gravel; 1980-05-26 to current/open; source msha-controller-operator-history