# Relationship history for MSHA mine 0405547

Current hierarchy: **Kelly Michael  Hickerson → NorCal Sand and Rock Inc. → NorCal Sand and Rock**

- 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:** Valley Sand and Rock, Inc → NorCal Sand and Rock; 2002-12-19 to 2020-03-17; source msha-controller-operator-history
- **controller_controls_mine:** James Bradley  Slender → NorCal Sand and Rock; 2002-12-19 to 2018-04-29; source msha-controller-operator-history
- **controller_controls_operator:** James Bradley  Slender → Valley Sand and Rock, Inc; 2002-12-19 to 2018-04-29; source msha-controller-operator-history
- **controller_controls_mine:** Brad  Slender et al → NorCal Sand and Rock; 2018-04-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brad  Slender et al → Valley Sand and Rock, Inc; 2018-04-30 to 2020-03-17; source msha-controller-operator-history
- **controller_controls_operator:** Darwin  Christ et al → Valley Sand and Rock, Inc; 2018-04-30 to 2020-03-17; source msha-controller-operator-history
- **controller_controls_operator:** K Michael  Hickerson et al → Valley Sand and Rock, Inc; 2018-04-30 to 2020-03-17; source msha-controller-operator-history
- **operator_operates_mine:** NorCal Sand and Rock Inc. → NorCal Sand and Rock; 2020-03-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kelly Michael  Hickerson → NorCal Sand and Rock; 2020-03-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kelly Michael  Hickerson → NorCal Sand and Rock Inc.; 2020-03-18 to current/open; source msha-controller-operator-history