# Relationship history for MSHA mine 2100860

Current hierarchy: **Martin Marietta Materials Inc → Barton Sand & Gravel → Hudson Pit 713 & Mill**

- 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:** Barton Contracting Company → Hudson Pit 713 & Mill; 1950-01-01 to 1983-02-28; source msha-controller-operator-history
- **controller_controls_mine:** Eugene  Barton → Hudson Pit 713 & Mill; 1950-01-01 to 1983-02-28; source msha-controller-operator-history
- **controller_controls_operator:** Eugene  Barton → Barton Contracting Company; 1950-01-01 to 1983-02-28; source msha-controller-operator-history
- **operator_operates_mine:** Barton Sand & Gravel → Hudson Pit 713 & Mill; 1983-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tiller Corp → Hudson Pit 713 & Mill; 1983-03-01 to 2021-05-03; source msha-controller-operator-history
- **controller_controls_operator:** Tiller Corp → Barton Sand & Gravel; 1983-03-01 to 2021-05-03; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Hudson Pit 713 & Mill; 2021-05-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Barton Sand & Gravel; 2021-05-04 to current/open; source msha-controller-operator-history