neath this fragmental material is found to be
solid lava, indicating the quiet nature of the
earlier eruptions. The lava rose through
north-south fissures some 5 miles long, but it
was a stiff, viscous mass that did not flow
freely. Consequently, it swelled up and, on
cooling, formed a long domelike mountain.
Afterward it was buried under the immense
accumulations produced by the violent eruptions.
If a valley like that of Chalone Creek had
been cut along the west side, the remaining
fragmental accumulations would have been
removed, and there would be no picturesque
pinnacles. On the other hand, if the eroded
materials could be replaced, the restored vol-
cano would be an outstanding peak of the
coast ranges, comparable with those of 8,000
feet and higher in the Ventura region today.
Several conditions have helped to preserve
an important remnant of the volcanic mass.
In the semiarid climate the rate of erosion is
less rapid than it was during long humid
periods in its earlier history. The climate
helps also in another way. Moisture enters
the pores of the rocks during the rains and
later evaporates from the surface, where it
deposits silica and other mineral matter which
it dissolves from the volcanic ash and lava
fragments. This hardens the surface of the
rock and protects the softer materials within.
Where the crust breaks away the rock crum-
bles rapidly, and cavities several feet in diam-
etter have been hollowed out, some of which
may be seen along the trails.
Faulting likewise has protected the forma-
tion on the old west slope. A north-south belt
2 to 3 miles wide, which has sunk down
along fissures at the east and west sides, now
holds all that is left of the volcanic materials.
They have been swept away completely from
the areas of granite bedrock to the east and
the west, but the granite bulwarks delay ero-
sion and thus protect and preserve the sunken
area between. This belt sank more at the west
than at the east, so the layers of fragmental
materials are steeper now than they were
originally on the west slope of the volcano.
The strong westerly dip appears at many
places. It is particularly prominent along the
switchback trail that leads up from the tunnel
to the summit.
Vertical cracks that were formed by the
movements also are prominent, and they have
largely aided and guided the erosion that
shaped and separated the pinnacles. Unequal
hardness of the beds also has produced odd
forms, especially where a soft layer has crum-
bled and left a great block like a head perched
on a slender neck.
Both the lava core of the volcano and the
fragmental materials that came up through
the numerous craters are composed mainly of
rhyolite, a lava that is closely related to gran-
ite. If it had cooled slowly beneath the sur-
face it would have formed granite. Several
other types of lava are found, including small
amounts of basalt.
Flora and Fauna
The lower slopes of the monument are
thickly covered with a dense mantle of brush,
which is mostly chamise. Interspersed with
this brush are scattered stands of digger pine,
which is gradually spreading and some day
may comprise an extensive forest cover. In
the canyons and ravines are shady groves of
live oaks. Chamise is important in furnishing
food and protection for the monument's
wildlife, and the digger pines afford safe
roosting places for many of the larger birds.
Deer are common in the monument, as are
also raccoons, gray foxes, ground squirrels,
cottontails, and wood rats. Less frequently
seen are coyotes and bobcats.
Pinnacles National Monument is notable
for the variety and interest of its birdlife.
Approximately 95 species have been observed.
Rarest and most spectacular is the duck hawk.
Its close cousin, the prairie falcon, is more
common. The golden eagle is also present,
but of the monument's large birds, the turkey
vulture is most in evidence. In the vicinity of
the high cliffs, the white-throated swift and
his companions in flight, the violet-green
swallow, the tree swallow, and the cliff swal-
low may be seen. Other birds often seen are
the raven, sparrow hawk, black phoebe, the
California woodpecker, the California linnnet,
the mourning dove, the California jay, the
rock wren, and the western bluebird. The
white-crowned and the golden-crowned spar-
row are commonly seen during the winter.
How To Reach the Monument
The monument is open all year. It is just
off State Route 25, 35 miles south of Hollister,
and about the same distance north of King
City. In approaching the monument from the
north, leave U. S. 101 about 2 miles south of
Gilroy; from the south, at King City. Ap-
proaching from the San Joaquin Valley, the
best route is over Pacheco Pass, State Route
152. All roads are paved.
Visitor Use Fees
Automobile, house trailer, and motorcycle
permit fees are collected at entrance stations.
When vehicles enter at times when entrance
stations are unattended, it is necessary that
the permit be obtained before leaving the
park and be shown upon reentry. The fees
applicable to the park are not listed herein
because they are subject to change, but they
may be obtained in advance of a visit by ad-
dressing a request to the superintendent.
All National Park fees are deposited as
revenue in the U. S. Treasury; they offset, in
part, appropriations made for operating and
maintaining the National Park System.
Camping and Picnicking
You may camp and picnic in the headquar-
ters area. Facilities, which are available with-
out charge, include suitable tent or trailer
space with table, fireplace, spring water, and
East entrance to monument
Camel Rock from Caves Trail