# Relationship history for MSHA mine 1800795

Current hierarchy: **Roland  Karbaum → Ryan Farms LLC → Merrick Sand and Gravel Massey Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Roland  Karbaum et al → Merrick Sand and Gravel Massey Plant; 2010-05-17 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ryan Farms LLC → Merrick Sand and Gravel Massey Plant; 2014-10-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roland  Karbaum et al → Ryan Farms LLC; 2014-10-16 to current/open; source msha-controller-operator-history