# Relationship history for MSHA mine 4700221

Current hierarchy: **Graymont Ltd → Western Lime Corp → Knowles Quarry And Mill**

- 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:** Western Lime Corp → Knowles Quarry And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael  Nast et al → Knowles Quarry And Mill; 1950-01-01 to 2012-03-29; source msha-controller-operator-history
- **controller_controls_operator:** Michael  Nast et al → Western Lime Corp; 1950-01-01 to 2012-03-29; source msha-controller-operator-history
- **controller_controls_mine:** Graymont Ltd → Knowles Quarry And Mill; 2012-03-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Graymont Ltd → Western Lime Corp; 2012-03-30 to current/open; source msha-controller-operator-history