# Relationship history for MSHA mine 2602122

Current hierarchy: **Wirthlin Kenneth Jay-Dan Keiserman → Heritage Sand & Gravel → Powerscreen #1**

- 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:** Heritage Sand & Gravel → Powerscreen #1; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Wirthlin Kenneth Jay-Dan Keiserman Et Al → Powerscreen #1; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wirthlin Kenneth Jay-Dan Keiserman Et Al → Heritage Sand & Gravel; 1989-08-01 to current/open; source msha-controller-operator-history