# Relationship history for MSHA mine 0501850

Current hierarchy: **Jaqueline  Simkin → Denver Brick Company → Dawson**

- 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:** Denver Brick & Pipe Company → Dawson; 1950-01-01 to 1984-01-19; source msha-controller-operator-history
- **controller_controls_mine:** Kevin  Croke → Dawson; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kevin  Croke → Denver Brick & Pipe Company; 1950-01-01 to 1984-01-19; source msha-controller-operator-history
- **operator_operates_mine:** Denver Brick Company → Dawson; 1984-01-20 to 1990-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Harold W  Emrich  et al → Dawson; 1984-01-20 to 1990-03-14; source msha-controller-operator-history
- **controller_controls_operator:** Harold W  Emrich  et al → Denver Brick Company; 1984-01-20 to 1990-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Jaqueline  Simkin → Dawson; 1990-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Denver Brick Company → Dawson; 1990-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jaqueline  Simkin → Denver Brick Company; 1990-03-15 to current/open; source msha-controller-operator-history