# Relationship history for MSHA mine 4604459

Current hierarchy: **Massey Energy Company → Douglas Pocahontas Coal Company → No 21 Mine**

- 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:** Call & Ramsey → No 21 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Valiunas J K → No 21 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Pounding Mill Coal Co Inc → No 21 Mine; 1974-06-01 to 1974-12-20; source msha-controller-operator-history
- **controller_controls_operator:** Call & Ramsey → Pounding Mill Coal Co Inc; 1974-06-01 to 1974-12-20; source msha-controller-operator-history
- **operator_operates_mine:** Douglas Pocahontas Coal Corp → No 21 Mine; 1974-12-21 to 1978-10-05; source msha-controller-operator-history
- **controller_controls_operator:** Valiunas J K → Douglas Pocahontas Coal Corp; 1974-12-21 to 1978-10-05; source msha-controller-operator-history
- **operator_operates_mine:** Douglas Pocahontas Coal Company → No 21 Mine; 1978-10-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Massey Energy Company → No 21 Mine; 1978-10-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Massey Energy Company → Douglas Pocahontas Coal Company; 1978-10-06 to current/open; source msha-controller-operator-history