# Relationship history for MSHA mine 0404634

Current hierarchy: **Taiheiyo Cement Corp → Calportland Construction → Rocky Canyon 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Steven F  Will Et Al → Rocky Canyon Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rocky Canyon Sand & Gravel Inc → Rocky Canyon Plant; 1983-04-01 to 1985-06-16; source msha-controller-operator-history
- **controller_controls_mine:** David P  Grimsley → Rocky Canyon Plant; 1983-04-01 to 1985-06-16; source msha-controller-operator-history
- **controller_controls_operator:** David P  Grimsley → Rocky Canyon Sand & Gravel Inc; 1983-04-01 to 1985-06-16; source msha-controller-operator-history
- **operator_operates_mine:** Union Asphalt Inc → Rocky Canyon Plant; 1985-06-17 to 2008-03-26; source msha-controller-operator-history
- **controller_controls_operator:** Steven F  Will Et Al → Union Asphalt Inc; 1985-06-17 to 2008-03-26; source msha-controller-operator-history
- **controller_controls_operator:** Andy C  Hermreck Et Al → Union Asphalt Inc; 1985-06-17 to 2008-03-26; source msha-controller-operator-history
- **controller_controls_mine:** Taiheiyo Cement Corp → Rocky Canyon Plant; 1990-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Calportland Construction → Rocky Canyon Plant; 2008-03-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → Calportland Construction; 2008-03-27 to current/open; source msha-controller-operator-history