Reconnaissance over-view of the geology of Paradigm
A brief report by David G. Howell for Ren Harris
February 15, 2016
The Paradigm vineyard lies between the Yountville Hill and the foothills of the Mayacamas Mountains. The vineyard lies solely on a northeast trending alluvial fan sourced from an unnamed drainage north of Hopper Creek (figure 1). The watershed for the fan reaches to the crest of the ridge between Dry Creek and the Napa Valley. The geology of the area from east to west involves: ~ 9 to 2.7 million year old andesite volcanic rocks of the Sonoma volcanic, the West Napa fault and the ~ 140 to ~ 80 million year old quartz-feldspar sedimentary strata of the Great Valley sequence (GVs) - deep sea sediments sourced from the then active Sierra Nevada volcanic arc (figure 2).
The fan is of very low relief dipping gently to the northeast. Total relief from the RR tracks to the top of the fan is ~ 30 meters. The material of the fan is clay, sand and rock fragments up to 5 inches in size. Most of the material is smaller that half an inch. The dark soil is rich in organic material. A random sampling of 100 pebbles indicates over 95 percent of the rock fragments are volcanic. Rare but distinctive quarts rich sandstone were sampled. The finer grained shale of the Great Valley sequence likely makes up much of the clay fraction found in the vineyard. The Paradigm vineyard occupies a geologic space comparable to the vineyards directly North of Paradigm, albeit the Paradigm fan is smaller in size.
A detailed topographic map of the region surrounding the Paradigm fan. The blue line “streams” are computer generated hypothetical drainage locations based on the high resolution LIDAR imagery (figure 3). The pattern of the blue lines defines the shape of the Paradigm fan.
A cut out portion of the 1:100K digital geology map of the Napa Quadrangle compiled in 2010 by David L. Wagner and Carlos I. Gutierrez of the California Geologic Survey. The general extent of the Paradigm fan and the fan’s watershed are shown in yellow and green respectively.
LIDAR (Light Detection and Ranging) is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. These light pulses—combined with other data recorded by the airborne system— generate precise, three-dimensional information about the shape of the Earth and its surface characteristics. Data from the LIDAR image reveal hypothetical drainage channels that define the general shape of the Paradigm fan.