# Relationship history for MSHA mine 0103518

Current hierarchy: **Darrin K  Isbell → North Alabama Materials, Inc. → McCord Limestone Quarry**

- 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:** North Alabama Materials, Inc. → McCord Limestone Quarry; 2018-01-31 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brian K  McCord → McCord Limestone Quarry; 2018-01-31 to 2020-11-29; source msha-controller-operator-history
- **controller_controls_operator:** Brian K  McCord → North Alabama Materials, Inc.; 2018-01-31 to 2020-11-29; source msha-controller-operator-history
- **controller_controls_mine:** Darrin K  Isbell → McCord Limestone Quarry; 2020-11-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Darrin K  Isbell → North Alabama Materials, Inc.; 2020-11-30 to current/open; source msha-controller-operator-history