# Relationship history for MSHA mine 3502910

Current hierarchy: **Morgan Gertrude J → Sierra Cascade Equipment Inc → Young & Morgan Crushing Company**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Hill Lloyd M Inc → Young & Morgan Crushing Company; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Morgan Gertrude J → Young & Morgan Crushing Company; 1978-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Lloyd M Hill Construction Inc → Young & Morgan Crushing Company; 1979-01-01 to 1980-06-08; source msha-controller-operator-history
- **controller_controls_operator:** Hill Lloyd M Inc → Lloyd M Hill Construction Inc; 1979-01-01 to 1980-06-08; source msha-controller-operator-history
- **operator_operates_mine:** Sierra Cascade Equipment Inc → Young & Morgan Crushing Company; 1980-06-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Morgan Gertrude J → Sierra Cascade Equipment Inc; 1980-06-09 to current/open; source msha-controller-operator-history