# Relationship history for MSHA mine 1504607

Current hierarchy: **Martin Del Kerwyn → D K M Coal Corp → Dkm Coal Corporation**

- 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:** Parma Coals Inc No 1 → Dkm Coal Corporation; 1950-01-01 to 1983-09-20; source msha-controller-operator-history
- **controller_controls_mine:** Roy R  Crawford et al → Dkm Coal Corporation; 1950-01-01 to 1983-09-20; source msha-controller-operator-history
- **controller_controls_operator:** Roy R  Crawford et al → Parma Coals Inc No 1; 1950-01-01 to 1983-09-20; source msha-controller-operator-history
- **operator_operates_mine:** Black Oak Mining Company Inc → Dkm Coal Corporation; 1983-09-21 to 1985-11-25; source msha-controller-operator-history
- **controller_controls_mine:** Reading & Bates Corp → Dkm Coal Corporation; 1983-09-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Reading & Bates Corp → Black Oak Mining Company Inc; 1983-09-21 to 1985-11-25; source msha-controller-operator-history
- **operator_operates_mine:** D K M Coal Corp → Dkm Coal Corporation; 1985-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Martin Del Kerwyn → Dkm Coal Corporation; 1985-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Del Kerwyn → D K M Coal Corp; 1985-11-26 to current/open; source msha-controller-operator-history