# Relationship history for MSHA mine 3100799

Current hierarchy: **Dexter O  Gravley → Gravley Sand Works → Kendall Pit #3**

- 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:** Kendall Sand Works → Kendall Pit #3; 1950-01-01 to 1979-06-20; source msha-controller-operator-history
- **controller_controls_mine:** Kendall Sand Works → Kendall Pit #3; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kendall Sand Works → Kendall Sand Works; 1950-01-01 to 1979-06-20; source msha-controller-operator-history
- **controller_controls_mine:** Dexter O  Gravley → Kendall Pit #3; 1979-01-05 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Gravley Sand Works → Kendall Pit #3; 1979-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dexter O  Gravley → Gravley Sand Works; 1979-06-21 to current/open; source msha-controller-operator-history