# Relationship history for MSHA mine 3101963

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Materials, Inc. → Bonds Gravel 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:** Martin Marietta Materials Inc → Bonds Gravel Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Pless Brothers Gravel Company → Bonds Gravel Pit; 1984-03-01 to 1987-03-31; source msha-controller-operator-history
- **controller_controls_mine:** Henry L  Pless et al → Bonds Gravel Pit; 1984-03-01 to 1987-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Henry L  Pless et al → Pless Brothers Gravel Company; 1984-03-01 to 1987-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Bonds Gravel Pit → Bonds Gravel Pit; 1987-04-01 to 1991-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Ralph C  Bonds  et al → Bonds Gravel Pit; 1987-04-01 to 1991-05-31; source msha-controller-operator-history
- **controller_controls_operator:** Ralph C  Bonds  et al → Bonds Gravel Pit; 1987-04-01 to 1991-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Aggregates → Bonds Gravel Pit; 1991-06-01 to 2005-05-23; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates; 1991-06-01 to 2005-05-23; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Materials, Inc. → Bonds Gravel Pit; 2005-05-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Materials, Inc.; 2005-05-24 to current/open; source msha-controller-operator-history