# Relationship history for MSHA mine 4703636

Current hierarchy: **Wilks Brothers LLC → CARBO Ceramics, Inc. → CARBO Ceramics Marshfield Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Gary A  Kolstad et al → CARBO Ceramics Marshfield Plant; 1987-06-30 to 2020-06-30; source msha-controller-operator-history
- **operator_operates_mine:** CARBO Ceramics, Inc. → CARBO Ceramics Marshfield Plant; 2012-02-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gary A  Kolstad et al → CARBO Ceramics, Inc.; 2012-02-27 to 2020-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Wilks Brothers LLC → CARBO Ceramics Marshfield Plant; 2020-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wilks Brothers LLC → CARBO Ceramics, Inc.; 2020-07-01 to current/open; source msha-controller-operator-history