# Relationship history for MSHA mine 2301918

Current hierarchy: **CRH PLC → Holliday Sand & Gravel → HSS Q Portable Plant 2**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Ash Grove Cement Company → HSS Q Portable Plant 2; 1950-01-01 to 2018-06-20; source msha-controller-operator-history
- **operator_operates_mine:** Ash Grove Aggregates Inc → HSS Q Portable Plant 2; 1985-05-01 to 2021-03-10; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Ash Grove Aggregates Inc; 1985-05-01 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_mine:** Ash Grove Cement Company → HSS Q Portable Plant 2; 2008-08-01 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → HSS Q Portable Plant 2; 2018-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Ash Grove Aggregates Inc; 2018-06-21 to 2021-03-10; source msha-controller-operator-history
- **operator_operates_mine:** Holliday Sand & Gravel → HSS Q Portable Plant 2; 2021-03-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Holliday Sand & Gravel; 2021-03-11 to 2018-06-20; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Holliday Sand & Gravel; 2021-03-11 to current/open; source msha-controller-operator-history