# Relationship history for MSHA mine 3201086

Current hierarchy: **Tim  Barth; Tom  Griffith; Rob  Berg → North Dakota Proppant → Hazen Mine**

- 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:** North Dakota Proppant → Hazen Mine; 2022-08-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tom  Griffith et al → Hazen Mine; 2022-08-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tom  Griffith et al → North Dakota Proppant; 2022-08-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tim  Barth et al → North Dakota Proppant; 2022-08-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rob  Berg et al → North Dakota Proppant; 2022-08-18 to current/open; source msha-controller-operator-history