# Relationship history for MSHA mine 1200768

Current hierarchy: **Allyn  Beaver → Beaver Gravel Corporation → Beaver Materials**

- 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:** Allyn  Beaver → Beaver Materials; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Waverly Sand & Gravel → Beaver Materials; 1950-01-01 to 2000-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Leigh Ann  Bische → Beaver Materials; 1950-01-01 to 2000-07-09; source msha-controller-operator-history
- **controller_controls_operator:** Leigh Ann  Bische → Waverly Sand & Gravel; 1950-01-01 to 2000-07-09; source msha-controller-operator-history
- **operator_operates_mine:** Ma-Ri-Al Corp → Beaver Materials; 2000-07-10 to 2014-08-26; source msha-controller-operator-history
- **controller_controls_mine:** Allyn  Beaver → Beaver Materials; 2000-07-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Allyn  Beaver → Ma-Ri-Al Corp; 2000-07-10 to 2014-08-26; source msha-controller-operator-history
- **operator_operates_mine:** Beaver Gravel Corporation → Beaver Materials; 2014-08-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Allyn  Beaver → Beaver Gravel Corporation; 2014-08-27 to current/open; source msha-controller-operator-history