# Relationship history for MSHA mine 4102306

Current hierarchy: **T E  Norton Jr → Norton Ready Mix Company → Norton Ready Mix Company**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Norman & Son Ready Mix → Norton Ready Mix Company; 1950-01-01 to 1981-06-09; source msha-controller-operator-history
- **controller_controls_mine:** Norman Don → Norton Ready Mix Company; 1950-01-01 to 1981-06-09; source msha-controller-operator-history
- **controller_controls_operator:** Norman Don → Norman & Son Ready Mix; 1950-01-01 to 1981-06-09; source msha-controller-operator-history
- **operator_operates_mine:** Norton Ready Mix Company → Norton Ready Mix Company; 1981-06-10 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** T E  Norton Jr → Norton Ready Mix Company; 1981-06-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** T E  Norton Jr → Norton Ready Mix Company; 1981-06-10 to current/open; source msha-controller-operator-history