# Relationship history for MSHA mine 0404450

Current hierarchy: **Sherrie L  Zappola; David W  Yingling et at → Eagle Rock Inc → Grizzly Quarry**

- 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:** Eagle Rock Inc → Grizzly Quarry; 1980-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Larry E  Yingling → Grizzly Quarry; 1980-07-01 to 2025-01-05; source msha-controller-operator-history
- **controller_controls_operator:** Larry E  Yingling → Eagle Rock Inc; 1980-07-01 to 2025-01-05; source msha-controller-operator-history
- **controller_controls_mine:** David W  Yingling et at → Grizzly Quarry; 2025-01-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David W  Yingling et at → Eagle Rock Inc; 2025-01-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sherrie L  Zappola et al → Eagle Rock Inc; 2025-01-06 to current/open; source msha-controller-operator-history