# Relationship history for MSHA mine 0405432

Current hierarchy: **Taiheiyo Cement Corp → CalPortland → Grimes Rock a CalPortland Company**

- 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:** Taiheiyo Cement Corp → Grimes Rock a CalPortland Company; 1990-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Grimes Rock Inc → Grimes Rock a CalPortland Company; 2000-04-01 to 2024-12-27; source msha-controller-operator-history
- **controller_controls_mine:** Russell  Cochran → Grimes Rock a CalPortland Company; 2000-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Russell  Cochran → Grimes Rock Inc; 2000-04-01 to 2024-12-27; source msha-controller-operator-history
- **operator_operates_mine:** CalPortland → Grimes Rock a CalPortland Company; 2024-12-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → CalPortland; 2024-12-28 to current/open; source msha-controller-operator-history