# Relationship history for MSHA mine 3609878

Current hierarchy: **Frank J  Sgarlat; Carl S  Sgarlat → Airport Sand & Gravel Co Inc → Nicholson 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

- **controller_controls_mine:** Carl S  Sgarlat  et al → Nicholson Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Airport Sand & Gravel Co Inc → Nicholson Pit; 2010-08-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carl S  Sgarlat  et al → Airport Sand & Gravel Co Inc; 2010-08-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frank J  Sgarlat  et al → Airport Sand & Gravel Co Inc; 2010-08-31 to current/open; source msha-controller-operator-history