The uncertainty peculiar to all undertakings of this kind in the United States, arising from the necessity of appealing to each successive Legislature for the means of carrying on the work, and the disturbed state of the country during the whole time since we commenced operations, as also the unfortunate condition of the finances of the State, which has kept the treasury from one to two years behind in the payment of the legislative appropriations, have combined to render it difficult to arrange and carry out as systematic a plan for the conduct of the work as would, under more favorable circumstances, have been practicable.
Two ideas have, however, as far as possible, governed the survey in its operations: the first was, to make, as rapidly as could be done, a reconnoissance of the State, with the view of acquiring a knowledge of its general geological structure, the age of the various formations which occur in it, and as complete a general idea as possible of their range and extent, so that a foundation might be laid for the detailed work which would follow the preliminary examination; the second idea was, at the same time that the general examination was going on, to work up in detail certain more important districts, so that the public might have light on questions of economical interest, and at the same time be able to form an idea of what the work might be if ever carried to completion. Besides this, the natural history part of the survey was to be carried on, in connection with the geological work, as rapidly as possible, progress in all departments being necessarily proportioned to the varying amounts of the annual appropriations.
California is covered by a vast net-work of mountain ranges, separated by comparatively narrow valleys, with the exception of those of the Sacramento and San Joaquin, which do not, together, cover more than one-fifteenth of the area of the State. The remaining fourteen-fifteenths may be called mountainous, as the valleys include but a small portion of its surface. Into this mountainous region no accurate surveys have ever been carried; even the General Land Office work stops at the base of the mountains. A few ranch lines have been run among the moderately elevated portions of the Coast Ranges; but, as a general thing, the genuine Mexican grants were limited to the plains.
Without considerable topographical work in connection with the geological survey we should, then, be entirely unable to carry on our geological work with any pretense to accuracy, as we could neither locate our observations nor make our descriptions of the country intelligible. The authority for doing something for the increase of the geographical knowledge of the State is found in the clause of the act authorizing the survey, which requires “proper maps” to accompany the reports.
What has been done, up to the present time, in this department may be briefly recapitulated as follows:
A series of maps, forty-nine in number, has been compiled by Mr. Hoffmann from the original documents at the United States Surveyor-General’s Office; the scale of these is half an inch to the mile. They contain a compilation of nearly all that is known at that office in regard to the geography of the State. The maps, as thus blocked out, have been used by us in the field, by filling in the topography wherever our route has laid.
The maps which have been or are now being prepared for publication are:
1st. A map of the vicinity of the Bay of San Francisco, on a scale of half an inch to the mile, four feet by three; it extends from near Santa Cruz on the south to Napa on the north, and from the Pacific to Corral Hollow, east and west. The area of land which it covers is 4,248 square miles, which is just twice that of the State of Delaware, and only lacks two hundred square miles of equaling that of Connecticut. As near as can be ascertained, it contains one-third of the population of the State, and has about thirty inhabitants to the square mile—the average density of the population of California being but little over two to the square mile. This map, on which all the details of the topography are given, as minutely as the scale allows, is nearly completed, and will be soon ready for the engraver.
2d. A detailed map, on a scale of two inches to the mile, of the vicinity of Mount Diablo; this is about two and one-half by three feet in dimensions, and includes the most important coal mining district yet known to exist in the State. The map can be made ready for the engraver in a few days.
3d. A map of the Coast Ranges, from the Bay of Monterey south to Santa Barbara. It is about three feet by two and one-half in dimensions, is on a scale of six miles to the inch, and embraces about 16,000 square miles of territory. To complete it will require about another year’s work in the field with two sub-parties.