# Relationship history for MSHA mine 2900579

Current hierarchy: **Holley Fred W & Richard W Stevenson → Spider-Rock Mining Company → Section 27**

- 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:** Unc Mining & Milling → Section 27; 1950-01-01 to 1981-08-16; source msha-controller-operator-history
- **controller_controls_mine:** Unc Resources Inc → Section 27; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Unc Resources Inc → Unc Mining & Milling; 1950-01-01 to 1981-08-16; source msha-controller-operator-history
- **operator_operates_mine:** Spider-Rock Mining Company → Section 27; 1981-08-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Holley Fred W & Richard W Stevenson → Section 27; 1981-08-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holley Fred W & Richard W Stevenson → Spider-Rock Mining Company; 1981-08-17 to current/open; source msha-controller-operator-history