# Relationship history for MSHA mine 4101172

Current hierarchy: **Michael D  Smith → L S Sand & Gravel → Tascosa Plant**

- 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:** Hanson PLC → Tascosa Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Western Sand & Gravel Company Inc → Tascosa Plant; 1950-01-01 to 1987-12-31; source msha-controller-operator-history
- **controller_controls_mine:** W T  Griffin → Tascosa Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W T  Griffin → Western Sand & Gravel Company Inc; 1950-01-01 to 1987-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Pioneer International Ltd → Tascosa Plant; 1984-08-20 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Western Sand & Gravel Company Inc → Tascosa Plant; 1988-01-01 to 1998-02-04; source msha-controller-operator-history
- **controller_controls_mine:** Charles D  Baldwin → Tascosa Plant; 1988-01-01 to 1998-02-04; source msha-controller-operator-history
- **controller_controls_operator:** Charles D  Baldwin → Western Sand & Gravel Company Inc; 1988-01-01 to 1998-02-04; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Tascosa Plant; 1988-11-14 to 2007-08-22; source msha-controller-operator-history
- **operator_operates_mine:** Pioneer South Central Inc → Tascosa Plant; 1998-02-05 to 2000-08-03; source msha-controller-operator-history
- **controller_controls_operator:** Pioneer International Ltd → Pioneer South Central Inc; 1998-02-05 to 2000-08-03; source msha-controller-operator-history
- **operator_operates_mine:** Hanson Aggregates West Inc-South Central Reg. → Tascosa Plant; 2000-08-04 to 2003-05-09; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hanson Aggregates West Inc-South Central Reg.; 2000-08-04 to 2003-05-09; source msha-controller-operator-history
- **controller_controls_mine:** Michael D  Smith → Tascosa Plant; 2002-04-11 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hanson Aggregates → Tascosa Plant; 2003-05-10 to 2005-06-29; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Hanson Aggregates; 2003-05-10 to 2005-06-29; source msha-controller-operator-history
- **operator_operates_mine:** L S Sand & Gravel → Tascosa Plant; 2005-06-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael D  Smith → L S Sand & Gravel; 2005-06-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → Tascosa Plant; 2007-08-23 to 2021-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Hanson Aggregates; 2007-08-23 to 2005-06-29; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Tascosa Plant; 2021-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Hanson Aggregates; 2021-10-01 to 2005-06-29; source msha-controller-operator-history