# Relationship history for MSHA mine 1511678

Current hierarchy: **Thornsberry Donald → T-Berry Mining Company → No 1 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:** Michaels Robert K → No 1 Mine; 1978-03-01 to 1980-04-06; source msha-controller-operator-history
- **operator_operates_mine:** Knight Coal Company Inc → No 1 Mine; 1978-11-01 to 1979-12-09; source msha-controller-operator-history
- **controller_controls_operator:** Michaels Robert K → Knight Coal Company Inc; 1978-11-01 to 1979-12-09; source msha-controller-operator-history
- **controller_controls_mine:** Thornsberry Donald → No 1 Mine; 1979-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** T-Berry Mining Company → No 1 Mine; 1979-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thornsberry Donald → T-Berry Mining Company; 1979-12-10 to current/open; source msha-controller-operator-history