# Relationship history for MSHA mine 1300775

Current hierarchy: **John J  Derner → Shell Rock Products Inc → SHELL ROCK 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Shell Rock Sand & Gravel Company → SHELL ROCK PIT; 1950-01-01 to 1992-05-06; source msha-controller-operator-history
- **controller_controls_mine:** Irving W  Budlong → SHELL ROCK PIT; 1950-01-01 to 1992-05-06; source msha-controller-operator-history
- **controller_controls_operator:** Irving W  Budlong → Shell Rock Sand & Gravel Company; 1950-01-01 to 1992-05-06; source msha-controller-operator-history
- **operator_operates_mine:** Shell Rock Products Inc → SHELL ROCK PIT; 1992-05-07 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John J  Derner → SHELL ROCK PIT; 1992-05-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John J  Derner → Shell Rock Products Inc; 1992-05-07 to current/open; source msha-controller-operator-history