TESTING GRAPE VARIETIES 1ST THE VINIFERA REGIONS. 7 



The soil, hilly, usually fairly deep, and well drained, originated in 

 the decomposition of the Mariposa formation, consisting of dark shales 

 or slates, sandstones or quartzite sandstones, and conglomerates. 

 The large amount of iron present from decomposing volcanic-rock 

 material, where exposed to perfect weathering, gives the soil a deep 

 red color. Dark, shallow, conglomerate rocks sometimes outcrop in 

 spots, and rock fragments occur. The first few inches are often dark 

 red from the accumulation of organic matter. The first 8 to 18 inches 

 are usually brownish red clay or clay loam, underlain by 3 to 6 feet of 

 red clay or clay loam, with partially decomposed and weathered rock 

 formations, giving the subsoil a yellow appearance. 



Rock outcrops of conglomerates, chert, and slate occur in the higher 

 portions. The native vegetation is manzanita, chaparral, live oak 

 and yellow pine. 



The Colfax district is unique in the diversity of the fruit grown on 

 sidehill locations. 



GEYSERVILLE EXPERIMENT VINEYARD. 



The Geyserville Experiment Vineyard was established in the 

 spring of 1904, on the property of John D. Bosch, just east of Geyser- 

 ville, Sonoma Co., Cal., against a range of high hills (PL III, fig. 1), 

 236 feet above sea level. To a depth of 2\ to 3 feet the soil consists 

 of a uniform dark gravelly loam with a subsoil of light or yellowish 

 brown color, similar in texture to the topsoil. The soil is very mel- 

 low and carries considerable humus, which enables it to retain 

 moisture well. This type of soil extends over considerable areas 

 along the streams and the floor of the Sonoma Valley, having been 

 washed down from the shale, schist, and conglomerate hills. 



Soils of this type produce some of the choicest dry wines, both red 

 and white, of the State. 



LIVERMORE EXPERIMENT VINEYARD. 



The Livermore Experiment Vineyard was established in the spring 

 of 1904, on the property of Mr. C. H. Wente, 3 miles south of Liver- 

 more, Alameda Co., Cal., at an elevation of about 450 feet above sea 

 level. (See PL III, fig. 2.) The vineyard has a very uniform, level, 

 alluvial soil, derived from decomposed shales and schists, and is full 

 of rounded gravel washed down from the surrounding mountains. 



The surface soil is a dark-brown gravelly loam; the second, third, 

 and fourth feet gravelly sandy loam, replaced by gravelly sand in 

 the fifth foot. The humus decreases with the depth, while the gravel 

 increases, varying from 30 to 59 per cent. The proportion of clay 

 is greater than that of silt. This gives the soil a very heavy appear- 

 ance, the gravel sticking together very tightly when dry orpacked. No 

 alkali exists, but ground water is encountered at 5 or 6 feet in some 



