# Relationship history for MSHA mine 3607151

Current hierarchy: **Ibstock Plc → Glen-Gery Corp → Porter 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

- **controller_controls_mine:** Hanley Company → Porter Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ibstock Plc → Porter Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hanley Brick Inc → Porter Pit; 1981-06-01 to 1986-02-28; source msha-controller-operator-history
- **controller_controls_operator:** Hanley Company → Hanley Brick Inc; 1981-06-01 to 1986-02-28; source msha-controller-operator-history
- **operator_operates_mine:** Glen-Gery Corp → Porter Pit; 1986-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ibstock Plc → Glen-Gery Corp; 1986-03-01 to current/open; source msha-controller-operator-history