# Relationship history for MSHA mine 4201961

Current hierarchy: **Janice  Sackett; Larry  Jardine → Le Grand Johnson Construction Company → Portable Crusher C Unit**

- 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:** Larry  Jardine et al → Portable Crusher C Unit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Thyssen Mining Construction Inc & Hydrocarbon Mini → Portable Crusher C Unit; 1981-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hydrocarbon Resources Company → Portable Crusher C Unit; 1985-09-01 to 1990-06-10; source msha-controller-operator-history
- **controller_controls_operator:** Thyssen Mining Construction Inc & Hydrocarbon Mini → Hydrocarbon Resources Company; 1985-09-01 to 1990-06-10; source msha-controller-operator-history
- **operator_operates_mine:** Le Grand Johnson Construction Company → Portable Crusher C Unit; 1990-06-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Larry  Jardine et al → Le Grand Johnson Construction Company; 1990-06-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Janice  Sackett et al → Le Grand Johnson Construction Company; 1990-06-11 to current/open; source msha-controller-operator-history