# Relationship history for MSHA mine 4000781

Current hierarchy: **John H  Ford → Camden Gravel Company → Camden Mine & Mill**

- 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:** Camden Gravel Company → Camden Mine & Mill; 1950-01-01 to 1980-05-26; source msha-controller-operator-history
- **controller_controls_mine:** Hubbs Construction Company → Camden Mine & Mill; 1950-01-01 to 1980-05-26; source msha-controller-operator-history
- **controller_controls_operator:** Hubbs Construction Company → Camden Gravel Company; 1950-01-01 to 1980-05-26; source msha-controller-operator-history
- **operator_operates_mine:** Camden Gravel Company → Camden Mine & Mill; 1980-05-27 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John H  Ford  et al → Camden Mine & Mill; 1980-05-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John H  Ford  et al → Camden Gravel Company; 1980-05-27 to current/open; source msha-controller-operator-history