This data is an extract from the Napa county soils survey done in 1978. It is very coarse resolution and of limited utility.
Soils in the Vicinity of the Vineyard
Use and Practice Report All blocks
Description of Soil Types Referenced
Block 1 (Bachus) Soil Type Map
Upper Vineyards Soil Type Map Shows all type 136. Nonsense. Block5 is distinctly volcanic and different.
If replanting is to be considered the decision making process would benefit from a soils analysis by a professional vineyard soils consultant who would go to the site dig soil pits and report observations of the soil depth profile with supporting photographs, take away samples for mineral analysis, pH, nematodes.
See Camalie Vineyards Soil Analysis for reference to a typical Soils report.
Last Updated 6/13/13 Mark Holler, Pulido Vineyard Management 650-799-6571