# Relationship history for MSHA mine 1507018

Current hierarchy: **Rowlett Beecher → Blue Gem Coal Company → No 1 Mine**

- 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:** Blue Gem Coal Company → No 1 Mine; 1974-01-01 to 1974-05-03; source msha-controller-operator-history
- **controller_controls_mine:** Scarborough James C → No 1 Mine; 1974-01-01 to 1974-05-03; source msha-controller-operator-history
- **controller_controls_operator:** Scarborough James C → Blue Gem Coal Company; 1974-01-01 to 1974-05-03; source msha-controller-operator-history
- **operator_operates_mine:** E L Smith Sand & Gravel Inc → No 1 Mine; 1974-05-04 to 1976-05-03; source msha-controller-operator-history
- **controller_controls_mine:** Mitchell Berry → No 1 Mine; 1974-05-04 to 1976-05-03; source msha-controller-operator-history
- **controller_controls_operator:** Mitchell Berry → E L Smith Sand & Gravel Inc; 1974-05-04 to 1976-05-03; source msha-controller-operator-history
- **operator_operates_mine:** Blue Gem Coal Company → No 1 Mine; 1976-05-04 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rowlett Beecher → No 1 Mine; 1976-05-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rowlett Beecher → Blue Gem Coal Company; 1976-05-04 to current/open; source msha-controller-operator-history