# Relationship history for MSHA mine 4101112

Current hierarchy: **Norton W D → Nor-Tex Concrete Inc → Nor-Tex Sand**

- 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:** Julian Sand & Gravel Company → Nor-Tex Sand; 1950-01-01 to 1980-05-27; source msha-controller-operator-history
- **controller_controls_mine:** Julian Howard → Nor-Tex Sand; 1950-01-01 to 1980-05-27; source msha-controller-operator-history
- **controller_controls_operator:** Julian Howard → Julian Sand & Gravel Company; 1950-01-01 to 1980-05-27; source msha-controller-operator-history
- **operator_operates_mine:** Norton Sand Company → Nor-Tex Sand; 1980-05-28 to 1984-08-26; source msha-controller-operator-history
- **controller_controls_mine:** Norton Tom & Joe → Nor-Tex Sand; 1980-05-28 to 1984-08-26; source msha-controller-operator-history
- **controller_controls_operator:** Norton Tom & Joe → Norton Sand Company; 1980-05-28 to 1984-08-26; source msha-controller-operator-history
- **operator_operates_mine:** Norton Sand Company → Nor-Tex Sand; 1984-08-27 to 1985-11-19; source msha-controller-operator-history
- **controller_controls_mine:** T E  Norton Jr → Nor-Tex Sand; 1984-08-27 to 1985-11-19; source msha-controller-operator-history
- **controller_controls_operator:** T E  Norton Jr → Norton Sand Company; 1984-08-27 to 1985-11-19; source msha-controller-operator-history
- **operator_operates_mine:** Norton Sand Company → Nor-Tex Sand; 1985-11-20 to 1987-08-04; source msha-controller-operator-history
- **controller_controls_mine:** Norton W D → Nor-Tex Sand; 1985-11-20 to 1987-08-04; source msha-controller-operator-history
- **controller_controls_operator:** Norton W D → Norton Sand Company; 1985-11-20 to 1987-08-04; source msha-controller-operator-history
- **operator_operates_mine:** Norcon Of Texas Inc → Nor-Tex Sand; 1987-08-05 to 1989-03-21; source msha-controller-operator-history
- **controller_controls_mine:** Darden Kenneth → Nor-Tex Sand; 1987-08-05 to 1989-03-21; source msha-controller-operator-history
- **controller_controls_operator:** Darden Kenneth → Norcon Of Texas Inc; 1987-08-05 to 1989-03-21; source msha-controller-operator-history
- **operator_operates_mine:** Nor-Tex Concrete Inc → Nor-Tex Sand; 1989-03-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Norton W D → Nor-Tex Sand; 1989-03-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Norton W D → Nor-Tex Concrete Inc; 1989-03-22 to current/open; source msha-controller-operator-history