# Relationship history for MSHA mine 0401951

Current hierarchy: **Smith David D → Somis Sand & Rock Inc → Somis Pit**

- 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:** Somis Sand & Rock → Somis Pit; 1950-01-01 to 1981-03-19; source msha-controller-operator-history
- **controller_controls_mine:** Atkinson Richard M → Somis Pit; 1950-01-01 to 1981-03-19; source msha-controller-operator-history
- **controller_controls_operator:** Atkinson Richard M → Somis Sand & Rock; 1950-01-01 to 1981-03-19; source msha-controller-operator-history
- **operator_operates_mine:** Tapo Rock & Sand → Somis Pit; 1981-03-20 to 1988-09-24; source msha-controller-operator-history
- **controller_controls_mine:** William C  Brooks → Somis Pit; 1981-03-20 to 1988-09-24; source msha-controller-operator-history
- **controller_controls_operator:** William C  Brooks → Tapo Rock & Sand; 1981-03-20 to 1988-09-24; source msha-controller-operator-history
- **operator_operates_mine:** Somis Sand & Rock Inc → Somis Pit; 1988-09-25 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Smith David D → Somis Pit; 1988-09-25 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Smith David D → Somis Sand & Rock Inc; 1988-09-25 to current/open; source msha-controller-operator-history