# Relationship history for MSHA mine 1506746

Current hierarchy: **N S C Corp; Sibo Services Inc → Nugent Sand Company → Harmony Landing**

- 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:** Martin Marietta Aggregates → Harmony Landing; 1950-01-01 to 1987-01-22; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Harmony Landing; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates; 1950-01-01 to 1987-01-22; source msha-controller-operator-history
- **controller_controls_mine:** Sibo Services Inc et al → Harmony Landing; 1984-07-23 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Billy Holloway Aggregates Inc → Harmony Landing; 1987-01-23 to 1990-10-09; source msha-controller-operator-history
- **controller_controls_mine:** Holloway Materials Inc → Harmony Landing; 1987-01-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Holloway Materials Inc → Billy Holloway Aggregates Inc; 1987-01-23 to 1990-10-09; source msha-controller-operator-history
- **operator_operates_mine:** Nugent Sand Company → Harmony Landing; 1990-10-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Sibo Services Inc et al → Nugent Sand Company; 1990-10-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** N S C Corp et al → Nugent Sand Company; 1990-10-10 to current/open; source msha-controller-operator-history