# Relationship history for MSHA mine 3609649

Current hierarchy: **Mark G Walworth; Ted  Walworth → Walworth Quarries → Hickory Grove Pit  #1 &  #2**

- 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:** Mark G Walworth et al → Hickory Grove Pit  #1 &  #2; 1999-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Walworth Quarries → Hickory Grove Pit  #1 &  #2; 2008-07-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark G Walworth et al → Walworth Quarries; 2008-07-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ted  Walworth et al → Walworth Quarries; 2008-07-29 to current/open; source msha-controller-operator-history