# Relationship history for MSHA mine 1508757

Current hierarchy: **Farley John B → Circle F Coal Co → No 1 Surface 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

- **operator_operates_mine:** R C Coal Co → No 1 Surface Mine; 1975-09-03 to 1975-11-16; source msha-controller-operator-history
- **controller_controls_mine:** R C Coal Co → No 1 Surface Mine; 1975-09-03 to 1975-11-16; source msha-controller-operator-history
- **controller_controls_operator:** R C Coal Co → R C Coal Co; 1975-09-03 to 1975-11-16; source msha-controller-operator-history
- **operator_operates_mine:** Circle F Coal Co → No 1 Surface Mine; 1975-11-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Farley John B → No 1 Surface Mine; 1975-11-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Farley John B → Circle F Coal Co; 1975-11-17 to current/open; source msha-controller-operator-history