# Relationship history for MSHA mine 0900975

Current hierarchy: **Clarkes Block Company → C B Sand → C B Sand**

- 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:** Murray Sand Company → C B Sand; 1985-07-01 to 1998-08-04; source msha-controller-operator-history
- **controller_controls_mine:** Robert B Murray → C B Sand; 1985-07-01 to 1998-08-04; source msha-controller-operator-history
- **controller_controls_operator:** Robert B Murray → Murray Sand Company; 1985-07-01 to 1998-08-04; source msha-controller-operator-history
- **operator_operates_mine:** C B Sand → C B Sand; 1998-08-05 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Clarkes Block Company → C B Sand; 1998-08-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Clarkes Block Company → C B Sand; 1998-08-05 to current/open; source msha-controller-operator-history