*** Source: Thompson, Robert A., Historical and descriptive sketch of Sonoma County, California. Philadelphia: L.H. Everts & Co., 1877, 122 pgs. Notice: This data is donated to the Public Domain by TAG, 2004, and may be copied freely by anyone to anywhere. *** ---page 4--- TOPOGRAPHY. The main Coast Range, of which Monte Diablo is a well known and con- spicuous peak, continues northwesterly from Carquinez straits, and forms the water-shed between the Sacramento valley and the coast country. This range passes through Napa county, which bounds Sonoma on the east, and into and through the northeast corner of Sonoma county, reaching an elevation above the sea level of three thousand six hundred feet. The highest mountain in the county is Geyser peak, so called from its proximity to the Geyser springs. This peak is three thousand four hundred and seventy feet above the sea level. It is a prominent landmark, visible from nearly all parts of the county. The Gey- ser springs, a well-known California wonder, and a number of valuable quick- silver mines, are located in this part of the county. From Geyser peak almost all of the county of Sonoma may be seen, and the Pacific ocean, beyond the fair land on which it borders. A number of valleys extend southwesterly from the main chain of the Coast Range, described above, which widen gradually, and front on the north- ern shore of the bay of San Pablo. These valleys are separated from each other by spurs from the Main Range, running parallel with the valleys. First, on the east, we have the valley of Napa, which bounds Sonoma county on that side; then west of, and nearly parallel with it, Sonoma valley, from which the county takes its name; it forms, however, a very small portion of the county of Sonoma. West of Sonoma valley, and separated from it by a high range of hills, is the largest, most fertile, and most populous of all the valleys west of the great Sacramento plain. It fronts on the north shore of San Pablo bay, and extends from the bay shore inland for about sixty miles, and has an aver- age width of ten to twelve miles. The lower or most southerly section of this great valley is called Petaluma--the central portion is called Santa Rosa, and the most northerly portion is called Russian River valley. The three may be said to form one great valley, through which the San Francisco and North Pacific Railroad runs, from its terminus on tide-water, for sixty miles, without a cut more than ten feet deep on the entire line. The four great valleys which we have just mentioned are the chief topo- graphical features of Sonoma county. The hills separating Sonoma valley from the great Central valley, terminate at Santa Rosa. About twenty-five miles from its bay-shore, Sonoma valley, having gradually narrowed, merges into the great Central valley. West of the Central valley lies the immediate coast country. The southern section of the coast country lying just north of Marin county is celebrated for its dairy products. The hills are rolling, des- titute entirely of trees or brush, and covered with a rich sward of grass, kept green most of the year by its proximity to the ocean. This dairy-section ex- tends nearly to Russian river; along that river and north of it to the county line, the country is densely timbered. SMALLER VALLEYS. In addition to the principal valleys we have described, there are others equally beautiful and fertile, and, though smaller, are well worthy of a descrip- tion more in detail than the space at our command will permit. Alexander *** end ***