# Relationship history for MSHA mine 4300413

Current hierarchy: **Karen K Martel Revocable Trust → Calkins Sand & Gravel Inc → Portable Screen Plant St 72376**

- 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

- **controller_controls_mine:** Rita M  Calkins → Portable Screen Plant St 72376; 1950-01-01 to 2020-01-28; source msha-controller-operator-history
- **operator_operates_mine:** Calkins Sand & Gravel Inc → Portable Screen Plant St 72376; 1987-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rita M  Calkins → Calkins Sand & Gravel Inc; 1987-08-01 to 2020-01-28; source msha-controller-operator-history
- **controller_controls_mine:** Rita M Calkins Trust → Portable Screen Plant St 72376; 2020-01-29 to 2024-04-09; source msha-controller-operator-history
- **controller_controls_operator:** Rita M Calkins Trust → Calkins Sand & Gravel Inc; 2020-01-29 to 2024-04-09; source msha-controller-operator-history
- **controller_controls_mine:** Karen K Martel Revocable Trust → Portable Screen Plant St 72376; 2024-04-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Karen K Martel Revocable Trust → Calkins Sand & Gravel Inc; 2024-04-10 to current/open; source msha-controller-operator-history