# Relationship history for MSHA mine 3502882

Current hierarchy: **Robert B  Qualey → Silverton Sand & Gravel Company → Drift Creek 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:** Robert B  Qualey → Drift Creek Pit; 1978-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Three Way Portable Crushing → Drift Creek Pit; 1979-01-01 to 1979-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Wendell  Lux et al → Drift Creek Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Wendell  Lux et al → Three Way Portable Crushing; 1979-01-01 to 1979-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Dave  Hanson et al → Three Way Portable Crushing; 1979-01-01 to 1979-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Silverton Sand & Gravel Company → Drift Creek Pit; 1980-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert B  Qualey → Silverton Sand & Gravel Company; 1980-01-01 to current/open; source msha-controller-operator-history