# Relationship history for MSHA mine 3607190

Current hierarchy: **Robert W  Laing → Franklin Gravel Company → FRANKLIN GRVL. CO.**

- 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:** Robert W  Laing → FRANKLIN GRVL. CO.; 1978-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Franklin Gravel Company → FRANKLIN GRVL. CO.; 1981-06-01 to 1986-09-02; source msha-controller-operator-history
- **controller_controls_operator:** Robert W  Laing → Franklin Gravel Company; 1981-06-01 to 1986-09-02; source msha-controller-operator-history
- **operator_operates_mine:** Gierlach Crushing & Contracting → FRANKLIN GRVL. CO.; 1986-09-03 to 1994-05-17; source msha-controller-operator-history
- **controller_controls_mine:** Paul A  Gierlach Jr → FRANKLIN GRVL. CO.; 1986-09-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Paul A  Gierlach Jr → Gierlach Crushing & Contracting; 1986-09-03 to 1994-05-17; source msha-controller-operator-history
- **operator_operates_mine:** Franklin Gravel Company → FRANKLIN GRVL. CO.; 1994-05-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert W  Laing → Franklin Gravel Company; 1994-05-18 to current/open; source msha-controller-operator-history