# Relationship history for MSHA mine 1400767

Current hierarchy: **Gary L  Johnson; Pamela M  Johnson → Johnson Sand → Johnson Sand Plant 2**

- 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:** Salina Sand Company → Johnson Sand Plant 2; 1950-01-01 to 1995-05-09; source msha-controller-operator-history
- **controller_controls_mine:** Ballou Construction Company Inc → Johnson Sand Plant 2; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ballou Construction Company Inc → Salina Sand Company; 1950-01-01 to 1995-05-09; source msha-controller-operator-history
- **controller_controls_mine:** Pamela M  Johnson et al → Johnson Sand Plant 2; 1985-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Johnson Sand → Johnson Sand Plant 2; 1995-05-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Pamela M  Johnson et al → Johnson Sand; 1995-05-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gary L  Johnson et al → Johnson Sand; 1995-05-10 to current/open; source msha-controller-operator-history