BITUMEN—COAL. 
285 
There are several localities of bitumen in the vicinity of Los Angeles which I did not have the 
opportunity of examining. At one place it is said to form a large pond or lake about one 
quarter of a mile in diameter. This is the source from which the principal supply is obtained. 
The residents of Los Angeles make use of large quantities of the material for covering their 
buildings and for pavements. It enables them to make roofs, that are almost level, completely 
water-tight; and it is spread out upon them in the following manner : The asphalt is taken 
early in the morning, when it is cold and brittle, and broken into small fragments. It is then 
spread upon the roof, and the heat of the sun melts it down into one homogeneous crust. When 
the inclination of the roofs is great, or the asphalt is freshly applied, it runs off at the eaves, 
and is a source of annoyance to pedestrians. After a considerable quantity has thus run down, 
it is thrown up again, until, at last it becomes so much hardened that it is no longer made 
liquid by the sun. These roofs, when well made, are perfectly water-tight, and are very durable. 
The value of this material for making pavements, roofs, cements, and in the manufacture of gas 
and oil, cannot be lightly estimated, and it should be regarded as one of the valuable mineral 
productions of the State. 
COAL. 
The geological formation of the country examined by the Survey is not such as to indicate the 
existence of mineral coal of the age of the Carboniferous. The only indications of coal that 
were found were the bitumen springs, and the bituminous shales, of the Tertiary formations, 
near Los Angeles. It is possible that beds of compact coal exist deeper in the strata below the 
bituminous beds, but this can only be determined by deep and expensive boring. The proba¬ 
bility is, that if coal does exist, it is at such a great depth that it cannot be mined to advantage, 
or so cheaply as fuel can be furnished from other sources. 
Bellingham Bay Coal — Washington Territory .—Although this locality is far beyond the limits 
of the region explored by tbe survey, it is not deemed inappropriate to give the following facts, 
which were obtained in San Francisco. 
Coal from this locality was in use in the city in 1854 for burning in grates and for cooking, 
and gave genera] satisfaction. It is a compact and perfectly black bituminous coal, breaking 
with a brilliant conchoidal surface, and, in large masses, much resembles the carboniferous coal 
mined at Pittsburg, Pa. It burns freely, and leaves a fine, white ash, which appears to be 
very abundant, but may not be present in such quantity in the better or interior parts of the 
vein. Through the kindness of Lieutenant W. P. Trowbridge, of the United States engineers, 
who has examined the region, I am able to present the following extracts from a manuscript 
report made by him in August, 1853. 
“The coal strata exposed to view on Bellingham Bay are situated in latitude 48° 43', and 
occur in a series of stratified rocks, which dip at an angle of 70° from the horizon, and strike 
E. 15° N. The thickness of the series being about two thousand feet.” * * * * 
“ The coal beds enter the bank at right angles to the shore-line, and rise with a gradual slope 
to the height of about three hundred and fifty feet, at the distance of half a mile from the 
shore, where they are broken in a direction oblique to that of the beds, and fall off in abrupt 
ledges to their original level.” * * * * “From the sections it will be seen that 
there are ten workable seams of coal, interstratified with six or seven heavy beds of sandstone, 
and numerous strata of bituminous shale, slate, clay, iron-stone, and thin beds of sandstone. 
In two thousand feet the coal occupies about one hundred feet; the thick beds of sandstone about 
