110 ASPIIALTUM BED AT SANTA BAEBAEY. 



exposures of this stratum have been made in various spots, in order to determine the extent of 

 the deposit. Its greatest thickness appears to be at the eliif edge ; in some spots^ 600 yards 

 inland, it is not thicker than three feet. The veins of supply rise at angles nearly vertical, 

 varying from 3 inches to 4 feet in thickness. The mineral in the seam has a brown lustre ; 

 melts readily when heated ; when cold, has a brittle conchoidal fracture. At the western edge 

 of the cliff is a small cape stretching into the breakers some 80 yards, the extremity of which 

 appeared to be made up of asphalt. Masses of bitumen were washed ashore containing mussel 

 and other shore shells. The beach deepens so rapidly as to allow of no observations at ebb tide. 

 Following this cape back to the cliff, the strata are found to dip away from it on either side, 

 giving a curved form to the beds along the cliff edge. In crevices of the lamina of this curve 

 the asphalt has infiltrated laterally. The veins must have once poured out their mineral on 

 what was once a shore, on which are found the same shells of the present seas as were met at 

 San Luis Obispo upon the terrace. 



It is difficult to estimate the total quantity of bitumen here, but it must be very great ; 

 perhaps 300 acres of ground were occupied by the overflow, varying from 2 to 8 feet in thick- 

 ness. It is easy of access, because lying along the cliff, down which it would only require to 

 be sent by a "chute," and load a vessel with it below. Accurate search was made for some 

 spot where it was at present being forced up, but there did not appear to be any traces of 

 present action. 



The land is claimed by Mr. Hill, owner of a ranch in the vicinity, but squatting has taken 

 place close to these beds in the valley. Some claim is also made to it by Messrs. Palmer, Cook 

 & Co., of San Francisco. As the bitumen here is wholly solid, it is better adapted for shipping, 

 and some cargoes have been sent to San Francisco, where it can be delivered for seven dollars 

 per ton^ total charges. The upper portion of the bed is mixed with alluvial clay and beach 

 shells, but the great mass of the bitumen is pure ; it has a brownish-black color, without the 

 glossy black of the Cuban variety, and dissolves readily in spirits of turpentine. It is, however, 

 equally valuable for all purposes of manufacture, except that of varnish making, with the 

 Chapapote mineral. Considering its purity, abundance, and facility of transport, this bed of 

 asphalt may be looked upon as the most important one in the State. 



The strata found at the cliff edge are as follows, from above downwards: 



1. Bed of hard gray sand, including a calcareous layer filled with beach shells, 6 to 8 feet 

 thick, and is unconformable to the strata below. 



2. Whitish clay rock, with threads of asphalt between the laminte ; dip, 55° south 40° east ; 

 strike^ north 50° west, (magnetic.) Owing to its softness, this rock is worn by the tide into 

 small caves along the beach ; the inferior beds are darker colored, and in belts, a dark layer 

 two feet thick intercalating with the whitish layers, and repeated five times ; total thickness, 

 about 200 feet. 



3. Greenish arenaceous rock — a fine-grained rock, containing small round fragments of 

 quartz ; the bed exposed did not display any fossils ; has the same dip as the overlying white 

 rock ; not more than 60 feet thick was exposed when the valley bottom was reached, making 

 the total thickness of the exposed rocks 260 feet. 



On the surface cliff, near the cape or headland alluded to, is a collection of shells, of the same 



species as those lying on the shore below, mixed in with the gray sand of the cliff, showing 



hat, at the time of this outflow of asphalt, and for some time subsequent, this was the beach 



level. The calcareous layer which underlies this, generally four feet down, is a continuous 



