# Relationship history for MSHA mine 4103564

Current hierarchy: **T E  Norton Jr → Norton Development Company → Concord Materials**

- 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:** Ransdell Tom B → Concord Materials; 1985-03-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Concord Materials Inc → Concord Materials; 1989-06-01 to 1990-06-17; source msha-controller-operator-history
- **controller_controls_operator:** Ransdell Tom B → Concord Materials Inc; 1989-06-01 to 1990-06-17; source msha-controller-operator-history
- **operator_operates_mine:** Norton Development Company → Concord Materials; 1990-06-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** T E  Norton Jr → Concord Materials; 1990-06-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** T E  Norton Jr → Norton Development Company; 1990-06-18 to current/open; source msha-controller-operator-history