# Relationship history for MSHA mine 4606418

Current hierarchy: **Hawkins Denver A → Big Grassy Creek Coal Company → Grassy Creek #3**

- 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

- **controller_controls_mine:** Helmick Robert H → Grassy Creek #3; 1980-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Talbott-Marks Company Inc → Grassy Creek #3; 1981-10-01 to 1985-03-10; source msha-controller-operator-history
- **controller_controls_mine:** Talbott A W → Grassy Creek #3; 1981-10-01 to 1985-03-10; source msha-controller-operator-history
- **controller_controls_operator:** Talbott A W → Talbott-Marks Company Inc; 1981-10-01 to 1985-03-10; source msha-controller-operator-history
- **operator_operates_mine:** Robert H Helmick Inc → Grassy Creek #3; 1985-03-11 to 1985-07-22; source msha-controller-operator-history
- **controller_controls_operator:** Helmick Robert H → Robert H Helmick Inc; 1985-03-11 to 1985-07-22; source msha-controller-operator-history
- **operator_operates_mine:** Big Grassy Creek Coal Company → Grassy Creek #3; 1985-07-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hawkins Denver A Et Al → Grassy Creek #3; 1985-07-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hawkins Denver A Et Al → Big Grassy Creek Coal Company; 1985-07-23 to current/open; source msha-controller-operator-history