# Relationship history for MSHA mine 2200540

Current hierarchy: **Florence K  Parker → Parker Sand & Gravel LLC → Parker Sand and Gravel LLC**

- 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

- **controller_controls_mine:** John  Cockerham Jr  et al → Parker Sand and Gravel LLC; 1978-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hamilton Gravel Company → Parker Sand and Gravel LLC; 1981-07-01 to 1983-08-23; source msha-controller-operator-history
- **controller_controls_operator:** John  Cockerham Jr  et al → Hamilton Gravel Company; 1981-07-01 to 1983-08-23; source msha-controller-operator-history
- **controller_controls_operator:** Philip  Cockerham  et al → Hamilton Gravel Company; 1981-07-01 to 1983-08-23; source msha-controller-operator-history
- **operator_operates_mine:** Grant Gravel Company → Parker Sand and Gravel LLC; 1983-08-24 to 1993-03-31; source msha-controller-operator-history
- **controller_controls_mine:** James Michael  Grant → Parker Sand and Gravel LLC; 1983-08-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James Michael  Grant → Grant Gravel Company; 1983-08-24 to 1993-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Parker Sand & Gravel LLC → Parker Sand and Gravel LLC; 1993-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Florence K  Parker → Parker Sand and Gravel LLC; 1993-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Florence K  Parker → Parker Sand & Gravel LLC; 1993-04-01 to current/open; source msha-controller-operator-history