# Relationship history for MSHA mine 3609234

Current hierarchy: **John E  Preston → Preston & Preston Inc. → SKB QUARRY**

- 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:** John E  Preston → SKB QUARRY; 1997-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** JERRY L JOHNSON → SKB QUARRY; 2004-04-26 to 2007-05-21; source msha-controller-operator-history
- **controller_controls_mine:** Jerry L  Johnson → SKB QUARRY; 2004-04-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jerry L  Johnson → JERRY L JOHNSON; 2004-04-26 to 2007-05-21; source msha-controller-operator-history
- **operator_operates_mine:** Preston & Preston Inc. → SKB QUARRY; 2007-05-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John E  Preston → Preston & Preston Inc.; 2007-05-22 to current/open; source msha-controller-operator-history