# Relationship history for MSHA mine 2102922

Current hierarchy: **Hindermann Mark J & William A Fitzgerald → Rochester Sand & Gravel Inc → De Cook 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

- **controller_controls_mine:** Hindermann Mark J & William A Fitzgerald → De Cook Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rochester Sand & Gravel Inc → De Cook Pit; 1983-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hindermann Mark J & William A Fitzgerald → Rochester Sand & Gravel Inc; 1983-10-01 to current/open; source msha-controller-operator-history