# Relationship history for MSHA mine 0202108

Current hierarchy: **Donn  Merrick; Daryl  Merrick → A-Rock, Inc. → Gray Mountain 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** M J Buck"  Brown" → Gray Mountain Pit; 1980-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Material Supply Corp Inc → Gray Mountain Pit; 1982-10-01 to 1987-04-30; source msha-controller-operator-history
- **controller_controls_operator:** M J Buck"  Brown" → Material Supply Corp Inc; 1982-10-01 to 1987-04-30; source msha-controller-operator-history
- **operator_operates_mine:** Arrow Materials Corp → Gray Mountain Pit; 1987-05-01 to 1990-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Shirley  Powers → Gray Mountain Pit; 1987-05-01 to 1990-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Shirley  Powers → Arrow Materials Corp; 1987-05-01 to 1990-12-31; source msha-controller-operator-history
- **operator_operates_mine:** A-Rock, Inc. → Gray Mountain Pit; 1991-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Donn  Merrick  et al → Gray Mountain Pit; 1991-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donn  Merrick  et al → A-Rock, Inc.; 1991-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Daryl  Merrick  et al → A-Rock, Inc.; 1991-01-01 to current/open; source msha-controller-operator-history