# Relationship history for MSHA mine 4201985

Current hierarchy: **Taylor Blain → Ridge Rock Inc → Ridge Rock Incorporated**

- 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:** Delta Mining Company → Ridge Rock Incorporated; 1986-08-01 to 1989-04-25; source msha-controller-operator-history
- **controller_controls_mine:** Dahl Kent R → Ridge Rock Incorporated; 1986-08-01 to 1989-04-25; source msha-controller-operator-history
- **controller_controls_operator:** Dahl Kent R → Delta Mining Company; 1986-08-01 to 1989-04-25; source msha-controller-operator-history
- **operator_operates_mine:** Ridge Rock Inc → Ridge Rock Incorporated; 1989-04-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Taylor Blain → Ridge Rock Incorporated; 1989-04-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Taylor Blain → Ridge Rock Inc; 1989-04-26 to current/open; source msha-controller-operator-history