Chalk Hill, the appellation, is one of 13 in Sonoma County -a region of fine wine, remarkable beauty, and agricultural abundance. Unique biospheres distinguish Chalk Hill from the neighboring appellations - the cooler Russian River Valley to the west and the warmer Alexander Valley to the northeast. Elevations in Chalk Hill are higher; soil fertility is lower. In amazing proximity, the soils range from shallow to deep, from thin to thick, from gravel and rock to heavy clay. An old river bed caps one hill; an unusual serpentine vein ranges through another and, under the topsoil, is a distinctive layer of chalk-colored volcanic ash which inspired the name of Chalk Hill, the appellation, and the estate.