# Relationship history for MSHA mine 3200700

Current hierarchy: **Mark T  Thorson → MARK SAND & GRAVEL DAKOTA CO. → PLANT 3**

- 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:** Mark  Schultz → PLANT 3; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Doreen  Gutzmer  et al → PLANT 3; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Lake Sand & Gravel Inc → PLANT 3; 1986-07-01 to 1987-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Mark  Schultz → Lake Sand & Gravel Inc; 1986-07-01 to 1987-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Gutzmer Construction Inc → PLANT 3; 1987-04-01 to 2002-08-28; source msha-controller-operator-history
- **controller_controls_operator:** Doreen  Gutzmer  et al → Gutzmer Construction Inc; 1987-04-01 to 2002-08-28; source msha-controller-operator-history
- **controller_controls_operator:** Llewellyn  Gutzmer  et al → Gutzmer Construction Inc; 1987-04-01 to 2002-08-28; source msha-controller-operator-history
- **operator_operates_mine:** Mark Sand & Gravel Dakota Co. → PLANT 3; 2002-08-29 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mark T  Thorson → PLANT 3; 2002-09-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Thorson → Mark Sand & Gravel Dakota Co.; 2002-09-11 to current/open; source msha-controller-operator-history