# Relationship history for MSHA mine 3401375

Current hierarchy: **Read Mike → M & R Sand → M & R 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:** Martin Sand Company → M & R Sand; 1982-12-01 to 1987-03-03; source msha-controller-operator-history
- **controller_controls_mine:** Martin William M → M & R Sand; 1982-12-01 to 1987-03-03; source msha-controller-operator-history
- **controller_controls_operator:** Martin William M → Martin Sand Company; 1982-12-01 to 1987-03-03; source msha-controller-operator-history
- **operator_operates_mine:** M & R Sand → M & R Sand; 1987-03-04 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Read Mike → M & R Sand; 1987-03-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Read Mike → M & R Sand; 1987-03-04 to current/open; source msha-controller-operator-history