# Relationship history for MSHA mine 3610143

Current hierarchy: **Grant C McKnight → Natural Sand, Co, Inc → Varos Mine**

- 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:** Natural Sand, Co, Inc → Varos Mine; 2015-04-28 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Grant C McKnight → Varos Mine; 2015-04-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grant C McKnight → Natural Sand, Co, Inc; 2015-04-28 to current/open; source msha-controller-operator-history