# Relationship history for MSHA mine 4003309

Current hierarchy: **Howard L  Mercer → Turner Brothers Stone Of Crossville, Inc → Barnwell 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:** Howard L  Mercer → Barnwell Quarry; 1981-03-26 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Turner Brothers Stone Of Crossville, Inc → Barnwell Quarry; 2007-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howard L  Mercer → Turner Brothers Stone Of Crossville, Inc; 2007-11-14 to current/open; source msha-controller-operator-history