# Relationship history for MSHA mine 3400796

Current hierarchy: **John L  Coffman → John L Coffman → Coffman 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:** Granite Gravel Company → Coffman Pit; 1950-01-01 to 1980-04-13; source msha-controller-operator-history
- **controller_controls_mine:** E L  Irwin → Coffman Pit; 1950-01-01 to 1982-11-14; source msha-controller-operator-history
- **controller_controls_operator:** E L  Irwin → Granite Gravel Company; 1950-01-01 to 1980-04-13; source msha-controller-operator-history
- **operator_operates_mine:** John L Coffman → Coffman Pit; 1980-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John L  Coffman → Coffman Pit; 1980-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John L  Coffman → John L Coffman; 1980-04-14 to current/open; source msha-controller-operator-history