GEOGRAPHY AND TOPOGRAPHY. 
10 
and opposed by the east-west structure of the Santa Ynez Range, 
and the result is this convergence of ranges with the consequent 
formation of a high, structurally complex region. The Lompoc 
quadrangle is on the western outskirts of this region, and the lines 
of relief corresponding to the two lines of structure are here begin¬ 
ning to diverge and show their individuality in the two bounding 
ranges. 
SANTA MARIA VALLEY. 
Santa Maria River, which takes its rise in two profound valleys 
within the San Rafael Range, flows along the foot of this range at 
the north edge of the Santa Maria Valley. This valley is a wide 
flood plain with an even cultivated floor, surrounded by low terraces 
that fringe the base of the mountains on the northeast and rise into 
the Solomon Hills on the south. It opens out to the sea and forms 
the southern part of the low region lying between Pismo Beach in 
San Luis Obispo County and the Casmalia Hills. 
C ASM ALIA HILLS. 
The most prominent feature of the landscape south of the Santa 
Maria Valley is a long ridge with a level sky line running northwest¬ 
ward out to the ocean at Point Sal. This is the high ridge of the Cas¬ 
malia Hills, which rises abruptly from the Santa Maria Valley. Its 
highest point is Mount Lospe, 1,624 feet above the sea. The slope 
up to this ridge from the valley on the northeast is steep, but on the 
north the rise is more gradual over wide slopes of dune sand. On 
the southeast the ridge declines as it approaches Schumann Pass^ 
the low divide over which the railroad crosses from the Santa Maria 
Valley to Schumann Canyon; on the south it forks into successive 
ridges which slope gradually into terraced hilltops bordering Schu¬ 
mann Canyon; on the west it drops off abruptly into steep, rocky 
declivities that fringe the sea in the neighborhood of Point Sal. The 
ridges continue southeastward opposite Schumann Pass as far as 
Graciosa Canyon, where they sink under more recent sand formations 
and lose their character. South of Schumann Canyon the terraced 
slope continues in the San Antonio terrace as a wide plateau locally 
intersected by sharply defined U-sliaped canyons. The Casmalia 
Hills, particularly that portion north of Schumann Canyon, have a 
distinct individuality among the topographic features of the basin 
region, and may be regarded as a separate although small range 
allied in age and character with the bounding ranges. It is conform¬ 
able in trend with the San Rafael Mountains and forms a prominent 
headland jutting out to sea. 
Most of the ridges in these hills follow the strike of the beds. 
Their summits are characteristically of gentle incline; the side slopes 
