# Relationship history for MSHA mine 2300710

Current hierarchy: **John H Berra Construction Co → Pacific Sand & Gravel → Pacific Sand & Gravel Company**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Simpson Sand & Gravel Company Inc → Pacific Sand & Gravel Company; 1950-01-01 to 1979-11-25; source msha-controller-operator-history
- **controller_controls_mine:** Michael G  Simpson et al → Pacific Sand & Gravel Company; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael G  Simpson et al → Simpson Sand & Gravel Company Inc; 1950-01-01 to 1979-11-25; source msha-controller-operator-history
- **controller_controls_operator:** Mark T  Simpson et al → Simpson Sand & Gravel Company Inc; 1950-01-01 to 1979-11-25; source msha-controller-operator-history
- **operator_operates_mine:** Roads Unlimited Inc → Pacific Sand & Gravel Company; 1979-11-26 to 1980-05-06; source msha-controller-operator-history
- **controller_controls_mine:** Wyatt Leo R → Pacific Sand & Gravel Company; 1979-11-26 to 1980-05-06; source msha-controller-operator-history
- **controller_controls_operator:** Wyatt Leo R → Roads Unlimited Inc; 1979-11-26 to 1980-05-06; source msha-controller-operator-history
- **operator_operates_mine:** Meramec Materials Company → Pacific Sand & Gravel Company; 1980-05-07 to 1986-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Duncan Lloyd K Et Al → Pacific Sand & Gravel Company; 1980-05-07 to 1986-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Duncan Lloyd K Et Al → Meramec Materials Company; 1980-05-07 to 1986-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Pacific Sand & Gravel → Pacific Sand & Gravel Company; 1986-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John H Berra Construction Co → Pacific Sand & Gravel Company; 1986-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John H Berra Construction Co → Pacific Sand & Gravel; 1986-10-01 to current/open; source msha-controller-operator-history