# Relationship history for MSHA mine 3200185

Current hierarchy: **Schauer Walter Jr → Napoleon Sand & Gravel → GROSS PIT**

- 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:** Napoleon Sand & Gravel → GROSS PIT; 1950-01-01 to 1983-08-10; source msha-controller-operator-history
- **controller_controls_mine:** Schauer Walter Jr → GROSS PIT; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schauer Walter Jr → Napoleon Sand & Gravel; 1950-01-01 to 1983-08-10; source msha-controller-operator-history
- **operator_operates_mine:** Wishek Ready Mix → GROSS PIT; 1983-08-11 to 1986-05-13; source msha-controller-operator-history
- **controller_controls_mine:** Schauer Gerald W & Clarence Meidinger → GROSS PIT; 1983-08-11 to 1986-05-13; source msha-controller-operator-history
- **controller_controls_operator:** Schauer Gerald W & Clarence Meidinger → Wishek Ready Mix; 1983-08-11 to 1986-05-13; source msha-controller-operator-history
- **operator_operates_mine:** Napoleon Sand & Gravel → GROSS PIT; 1986-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schauer Walter Jr → Napoleon Sand & Gravel; 1986-05-14 to current/open; source msha-controller-operator-history