# Relationship history for MSHA mine 3400922

Current hierarchy: **Mark E  Krenz → Peerless Materials Company → Nelson 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:** O'Brien Rock Company Inc → Nelson Pit; 1950-01-01 to 1991-03-05; source msha-controller-operator-history
- **controller_controls_mine:** O'Brien Eugene → Nelson Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** O'Brien Eugene → O'Brien Rock Company Inc; 1950-01-01 to 1991-03-05; source msha-controller-operator-history
- **controller_controls_mine:** Mark E  Krenz → Nelson Pit; 1978-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Peerless Materials Company → Nelson Pit; 1991-03-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark E  Krenz → Peerless Materials Company; 1991-03-06 to current/open; source msha-controller-operator-history