# Relationship history for MSHA mine 3900889

Current hierarchy: **Chad  Willmott; Tom C  Willmott → Willmott Gravel → Willmott Gravel Inc**

- 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:** Willmott Gravel → Willmott Gravel Inc; 1950-01-01 to 1997-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Darwin  Willmott → Willmott Gravel Inc; 1950-01-01 to 1997-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Darwin  Willmott → Willmott Gravel; 1950-01-01 to 1997-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Willmott Gravel → Willmott Gravel Inc; 1997-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Chad  Willmott et al → Willmott Gravel Inc; 1997-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chad  Willmott et al → Willmott Gravel; 1997-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tom C  Willmott et al → Willmott Gravel; 1997-04-01 to current/open; source msha-controller-operator-history