# Relationship history for MSHA mine 1900010

Current hierarchy: **Seidl Nelson → Merrimack Granite Company Inc → Merrimack Granite Company Incorporated**

- 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

- **operator_operates_mine:** Forrest Road Granite Company → Merrimack Granite Company Incorporated; 1950-01-01 to 1985-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Stone Valmos H → Merrimack Granite Company Incorporated; 1950-01-01 to 1985-03-14; source msha-controller-operator-history
- **controller_controls_operator:** Stone Valmos H → Forrest Road Granite Company; 1950-01-01 to 1985-03-14; source msha-controller-operator-history
- **operator_operates_mine:** Merrimack Granite Company Inc → Merrimack Granite Company Incorporated; 1985-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Seidl Nelson → Merrimack Granite Company Incorporated; 1985-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Seidl Nelson → Merrimack Granite Company Inc; 1985-03-15 to current/open; source msha-controller-operator-history