Alta California

Map of Mexico including Upper California by S. Augustus Mitchell, Philadelphia, 1847.

Alta California was formed when Spain separated the Dominican Missions from the Franciscan Missions in approximately 1769.

During the Spanish and Mexican eras, Sonoma was an important location in what was then known as "Alta California".

Around 1844 Charles Wilkes published his Narrative of the United States Exploring Expedition documenting his five-year (1838-1842) expedition which included the following passage of "Upper California":

Upper California, which now belongs to the United States, contains about four hundred thousand square miles. The great proportion of it lies on the east of the California range of mountains, which traverse it from north to south, at from eighty to one hundred miles from the coast, and in a line parallel to it. The interior has been but little explored, but its characters are very well known, and that the whole central part of it is devoid of the necessaries for the subsistence of both man and beast, and never can become the abode of civilisation, and places somewhat a barrier to the approach to the "El Dorado." It is throughout an elevated plain, descending gradually to the south, the northern portion forming a kind of central basin between four and five thousand feet above the level of the sea, arid and destitute.

The climate of the western section of California is extremely salubrious, but thought to be unfavourable for agriculture. The year is divided into two seasons, the wet and dry ; the first is between December and March, and the latter the remainder of the year. During the wet season rain falls in deluges ; but in the dry not a drop is experienced, and drought occurs annually, and sometimes continues throughout the year, and everything that cannot be irrigated is destroyed.

The productions are numerous of this western section, which contains about twelve thousand square miles of tillable land.

Both Oregon and California are well adapted for raising of stock ; the former for its natural hay, and the latter for its nutritious grasses. Cattle thrive well- the whole year and require no housing or feeding.

The mineral wealth, in the precious metals, is now believed to be exhaustless, and has a range from the Umpqua to the Gulf of California, throughout which this geological formation extends. Besides gold, platinum, silver, copper, iron, tin, lead and mercury are found ; and sulphur in its crystallised state, is said also to exist in large quantities.

• Historic Timeline
  

• Wikipedia entry on Alta California.
  

• Pío de Jesus Pico, the last Mexican governor of Alta California.

• Charles Wilkes, U.S.N., Narrative of the United States Exploring Expedition During the Years of 1838, 1839, 1840, 1841, 1842.