Geography and topography. 
28 
of Canada Tortuga the steeper portion above the coastal bench is only 
100 feet high, and in the northwest corner of the mesa the main 
terrace and the coastal bench grade into each other and become 
practically one. 
SANTA YNEZ VALLEY AND SANTA RITA HILLS. 
Santa Y nez Itiver is the second of the two main drainage lines of 
the area, Los Alamos Creek, the next in size, being much subordinate 
to these two. The Santa Ynez rises in the high region north of Santa 
Barbara and flows westward between the Santa Ynez and San Rafael 
ranges. From the east edge of the Lompoc quadrangle, where these 
two ranges diverge, it flows slightly to the north of west, at the foot 
of the Santa Ynez Mountains. Its course is even more westerly than 
that of the Los Alamos Valley until it approaches the ocean, where 
the. nose of the Santa Ynez Range, as in the two ranges farther north, 
shows a tendency to change its orientation into greater conformity 
with the northwesterly course of the San Rafael Range. 
This stream has a low gradient of only one-fourth of 1 per cent. Its 
valley has a steep side on the south formed by the hills of the Santa 
Ynez Range, but it is widened on the north by the easy slopes of ter¬ 
races and santl hills, except at the Santa Rita Hills, which rise midway 
in the river’s course. 
r' 
The Santa Rita Hills form a small separate range .reaching a height 
of 1,300 feet and resembling in miniature the Purisima Hills. The 
range starts from the valley in several strike ridges running north¬ 
west, which join in the highest part of the range and then continue 
due west as a single ridge. The river follows a tortuous course be¬ 
tween this and the Santa Ynez Range and has cut cliffs in many places. 
On the north the Santa Rita Hills are divided from the Purisima 
Hills by the Santa Rita Valley, a low basin similar to some portions 
of the Santa Ynez Valley. 
The level floor cf the river valley, including the stream bed and the 
somewhat higher terrace-like flats on either side, ranges in width from 
a few hundred feet to about a mile until within 10 miles of the ocean, 
where it opens out into the Lompoc Valley, an alluvial flat several 
miles wide. 
TERRACED COAST. 
Pleistocene terraces border the coast for the greater part of the 
distance around the Guadalupe and Lompoc quadrangles. The 
great Burton Mesa terrace has already been mentioned. Beyond the 
valleys to the north and south of this mesa similar terraced areas 
extend widely and in places to a considerable distance inland, but no¬ 
where else with so gentle a slope as is exhibited on the Burton Mesa. 
