# Relationship history for MSHA mine 1510507

Current hierarchy: **David F  May → Mare Creek Sand Company Inc → Dwale Tipple**

- 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

- **operator_operates_mine:** Continental Coal Sales Corp → Dwale Tipple; 1977-04-01 to 1981-01-12; source msha-controller-operator-history
- **controller_controls_mine:** Continental Resources & Mineral Corp → Dwale Tipple; 1977-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Continental Resources & Mineral Corp → Continental Coal Sales Corp; 1977-04-01 to 1981-01-12; source msha-controller-operator-history
- **controller_controls_mine:** David F  May → Dwale Tipple; 1979-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mare Creek Sand Company Inc → Dwale Tipple; 1981-01-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David F  May → Mare Creek Sand Company Inc; 1981-01-13 to current/open; source msha-controller-operator-history