METAMORPHISM IN OIL-BEARING SHALE 753 
perature of the gases upon their issue “‘to be so high that the hand 
could not for a moment bear the heat.” It is not known to the 
writers whether these fires are still burning. 
TYPICAL OCCURRENCES OF BURNT SHALE 
The Santa Maria oil district in northern Santa Barbara County is 
rich in outcrops of rose-colored shale and other products of the burn- 
ing process, these occurring in eight or ten separate localities. The 
best examples are along the ridge bordering the Santa Maria Valley 
some eight miles southwest of Santa Maria; on the north and south 
sides of Graciosa Ridge, a similar distance south of that town; and 
on Redrock Mountain, four miles southeast of Los Alamos. In each 
of these regions every stage of alteration is exhibited from the slightly 
discolored shale to hard slag-like rocks of varying shades of red and 
black (see Fig. 2). The area of altered shale in the different locali- 
ties varies from a small one of some hundred square feet to one of 
half a square mile or more, as at Redrock Mountain. They are in 
every case surrounded by unaltered, usually soft, white, diatoma- 
ceous shale, which in the majority of cases shows the planes of strati- 
fication (see Fig. 1). No case was observed in which a sign of strati- 
fication was left in the baked shale. In every case the shale in 
the neighborhood is bituminous and asphalt deposits are usually 
adjacent. 
The largest area of altered shale in this region is on the summit 
and surrounding ridges of Redrock Mountain south of Los Alamos. 
This is the highest of the hills in the basin region between the San 
Rafael and Santa Ynez Mountains, being 1,968 feet above the sea, 
while the usual height of the summits round about is from 1,000 to 
1,500 feet. It seems to owe its prominence, at least in part, to the 
metamorphosed shale forming its summit. In the case likewise of 
the 800-foot hill on the southeast side of the Southern Pacific Railroad 
coast line at Schumann Pass, the capping of volcanic-looking rock 
of this same character seems to have caused the topographic :elief. 
The metamorphism in these cases probably took place a long time 
ago. At Redrock Mountain, in places in contact with the altered 
shale, are great deposits of asphalt and a large area of shale impreg- 
nated with bitumen. 
