# Relationship history for MSHA mine 2002868

Current hierarchy: **Amber  Hoover; Amy  Watson; James  Sturrus Jr → High Grade Materials Co → Doster Pit**

- 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:** Doster Sand & Gravel Lp → Doster Pit; 1991-09-01 to 2005-04-17; source msha-controller-operator-history
- **controller_controls_mine:** Joseph P  Langkamp → Doster Pit; 1991-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Joseph P  Langkamp → Doster Sand & Gravel Lp; 1991-09-01 to 2005-04-17; source msha-controller-operator-history
- **controller_controls_mine:** James P  Sturrus → Doster Pit; 1998-05-01 to 2019-04-30; source msha-controller-operator-history
- **operator_operates_mine:** High Grade Materials Co → Doster Pit; 2005-04-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James P  Sturrus → High Grade Materials Co; 2005-04-18 to 2019-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Amber  Hoover et al → Doster Pit; 2019-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amber  Hoover et al → High Grade Materials Co; 2019-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James  Sturrus Jr et al → High Grade Materials Co; 2019-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amy  Watson et al → High Grade Materials Co; 2019-05-01 to current/open; source msha-controller-operator-history