# Relationship history for MSHA mine 2002704

Current hierarchy: **Brent  Gerken; Michael J  Gerken → Gerken Materials Inc. → Round Lake**

- 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:** Karen S  Wells et al → Round Lake; 1982-12-28 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Wells Sand & Gravel → Round Lake; 1983-07-01 to 1984-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Karen S  Wells et al → Wells Sand & Gravel; 1983-07-01 to 1984-04-30; source msha-controller-operator-history
- **controller_controls_operator:** John W  Wells et al → Wells Sand & Gravel; 1983-07-01 to 1984-04-30; source msha-controller-operator-history
- **operator_operates_mine:** Round Lake Sand & Gravel → Round Lake; 1984-05-01 to 2007-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Donald  MacRitchie  et al → Round Lake; 1984-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald  MacRitchie  et al → Round Lake Sand & Gravel; 1984-05-01 to 2007-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Ronald  MacRitchie  et al → Round Lake Sand & Gravel; 1984-05-01 to 2007-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Gerken Materials Inc. → Round Lake; 2008-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brent  Gerken et al → Round Lake; 2008-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brent  Gerken et al → Gerken Materials Inc.; 2008-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael J  Gerken et al → Gerken Materials Inc.; 2008-01-01 to current/open; source msha-controller-operator-history