# Relationship history for MSHA mine 2302509

Current hierarchy: **CRH PLC → Holliday Sand & Gravel → Riverside Dredge**

- 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:** Ash Grove Cement Company → Riverside Dredge; 2008-08-01 to 2018-06-20; source msha-controller-operator-history
- **operator_operates_mine:** Holliday Sand & Gravel → Riverside Dredge; 2016-07-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Holliday Sand & Gravel; 2016-07-06 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Riverside Dredge; 2018-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Holliday Sand & Gravel; 2018-06-21 to current/open; source msha-controller-operator-history