# Relationship history for MSHA mine 4607635

Current hierarchy: **Helmick Robert H → Robert H Helmick Inc → Dyers Run Surface Mine - East**

- 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 → Dyers Run Surface Mine - East; 1980-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hawkins Denver A Et Al → Dyers Run Surface Mine - East; 1987-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Webster Coal'S Inc → Dyers Run Surface Mine - East; 1988-12-01 to 1991-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Hawkins Denver A Et Al → Webster Coal'S Inc; 1988-12-01 to 1991-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Dulaney Lowell J → Dyers Run Surface Mine - East; 1988-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Braxton Minerals Inc → Dyers Run Surface Mine - East; 1991-05-01 to 1991-08-04; source msha-controller-operator-history
- **controller_controls_operator:** Dulaney Lowell J → Braxton Minerals Inc; 1991-05-01 to 1991-08-04; source msha-controller-operator-history
- **operator_operates_mine:** Robert H Helmick Inc → Dyers Run Surface Mine - East; 1991-08-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Helmick Robert H → Robert H Helmick Inc; 1991-08-05 to current/open; source msha-controller-operator-history