# Relationship history for MSHA mine 3401224

Current hierarchy: **Mark D  Matthews → T & M Sand & Gravel → Watts 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:** Steel Ball Inc → Watts Pit; 1979-08-01 to 1992-08-24; source msha-controller-operator-history
- **controller_controls_mine:** J B  Harriman → Watts Pit; 1979-08-01 to 1992-08-24; source msha-controller-operator-history
- **controller_controls_operator:** J B  Harriman → Steel Ball Inc; 1979-08-01 to 1992-08-24; source msha-controller-operator-history
- **operator_operates_mine:** T & M Sand & Gravel → Watts Pit; 1992-08-25 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mary E  Matthews → Watts Pit; 1992-08-25 to 2016-01-14; source msha-controller-operator-history
- **controller_controls_operator:** Mary E  Matthews → T & M Sand & Gravel; 1992-08-25 to 2016-01-14; source msha-controller-operator-history
- **controller_controls_mine:** Mark D  Matthews → Watts Pit; 2016-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark D  Matthews → T & M Sand & Gravel; 2016-01-15 to current/open; source msha-controller-operator-history