# Relationship history for MSHA mine 2901999

Current hierarchy: **Norman C  Ribble → Ribble Contracting Inc → RIBBLE CRUSHER #1**

- 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

- **controller_controls_mine:** Norman C  Ribble → RIBBLE CRUSHER #1; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ribble Contracting Inc → RIBBLE CRUSHER #1; 1985-08-01 to 1986-08-04; source msha-controller-operator-history
- **controller_controls_operator:** Norman C  Ribble → Ribble Contracting Inc; 1985-08-01 to 1986-08-04; source msha-controller-operator-history
- **controller_controls_mine:** Bill  Aubrey → RIBBLE CRUSHER #1; 1986-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Blaze Construction Inc → RIBBLE CRUSHER #1; 1986-08-05 to 1986-09-14; source msha-controller-operator-history
- **controller_controls_operator:** Bill  Aubrey → Blaze Construction Inc; 1986-08-05 to 1986-09-14; source msha-controller-operator-history
- **operator_operates_mine:** Ribble Contracting Inc → RIBBLE CRUSHER #1; 1986-09-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Norman C  Ribble → Ribble Contracting Inc; 1986-09-15 to current/open; source msha-controller-operator-history