# Relationship history for MSHA mine 4702585

Current hierarchy: **Mark S  Rosenbaum → Rosenbaum Crushing & Excavating → PORTABLE UNIT NO. 1**

- 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:** Erickson Crushing → PORTABLE UNIT NO. 1; 1979-01-01 to 1983-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Erickson Gilman → PORTABLE UNIT NO. 1; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Erickson Gilman → Erickson Crushing; 1979-01-01 to 1983-08-22; source msha-controller-operator-history
- **operator_operates_mine:** Rosenbaum Crushing & Excavating → PORTABLE UNIT NO. 1; 1983-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mark S  Rosenbaum → PORTABLE UNIT NO. 1; 1983-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark S  Rosenbaum → Rosenbaum Crushing & Excavating; 1983-08-23 to current/open; source msha-controller-operator-history