# Relationship history for MSHA mine 0102860

Current hierarchy: **Shakespeare Oil Company Inc; T & T Oil Company Inc → Covington Stone Company → Leesburg 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:** Shakespeare Oil Company Inc et al → Leesburg Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Covington Stone Company → Leesburg Quarry; 1990-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Shakespeare Oil Company Inc et al → Covington Stone Company; 1990-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** T & T Oil Company Inc et al → Covington Stone Company; 1990-05-01 to current/open; source msha-controller-operator-history