 In addition, Zamora silty clay loam is found in several large patches on the valley floor; Zamora silty clay loam is a grayish brown firm, sticky and plastic soil type and is also characteristic of alluvial fans; it has a neutral pH and occurs at minimum depths of about two meters.Due to the economic demand for wine grapes in this region, pressure began in the 1980s to develop some of the Bennett Valley soils for viticulture.Economic factors of land scarcity for upscale residential development and for premium wine grape cultivation led to an explosion of land values in Bennett Valley starting generally in the 1980s.