# Relationship history for MSHA mine 0404990

Current hierarchy: **Hart Don → Sand Pebble Suppliers Inc → Pomona 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:** Sand Pebble Suppliers Inc → Pomona Pit; 1988-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hart Don → Pomona Pit; 1988-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hart Don → Sand Pebble Suppliers Inc; 1988-12-01 to current/open; source msha-controller-operator-history