# Relationship history for MSHA mine 4503007

Current hierarchy: **Barbara  Dickinson → Two Rivers Sand & Gravel, Inc. → Two Rivers Sand & Gravel 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Two Rivers Sand & Gravel, Inc. → Two Rivers Sand & Gravel Pit; 1983-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bruce L  Dickinson → Two Rivers Sand & Gravel Pit; 1983-06-01 to 2017-03-04; source msha-controller-operator-history
- **controller_controls_operator:** Bruce L  Dickinson → Two Rivers Sand & Gravel, Inc.; 1983-06-01 to 2017-03-04; source msha-controller-operator-history
- **controller_controls_mine:** Barbara  Dickinson et al → Two Rivers Sand & Gravel Pit; 2017-03-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Barbara  Dickinson et al → Two Rivers Sand & Gravel, Inc.; 2017-03-05 to current/open; source msha-controller-operator-history