# Relationship history for MSHA mine 1900756

Current hierarchy: **Douglas J  Macone → Assabet Sand & Gravel Company Inc → M Kristoff 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:** R L Culley Inc → M Kristoff Pit; 1950-01-01 to 1980-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Culley Robert L → M Kristoff Pit; 1950-01-01 to 1980-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Culley Robert L → R L Culley Inc; 1950-01-01 to 1980-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Charles  Greenough → M Kristoff Pit; 1950-01-01 to 2006-10-25; source msha-controller-operator-history
- **operator_operates_mine:** Assabet Sand & Gravel Company Inc → M Kristoff Pit; 1980-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Charles  Greenough → Assabet Sand & Gravel Company Inc; 1980-06-01 to 2006-10-25; source msha-controller-operator-history
- **controller_controls_mine:** Douglas J  Macone → M Kristoff Pit; 2006-10-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Douglas J  Macone → Assabet Sand & Gravel Company Inc; 2006-10-26 to current/open; source msha-controller-operator-history