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the late 19th century.
Today, Palo Duro Canyon is one of
the best-known landmarks in Texas, a
tribute to the industry and vision of
local people, who have publicized the
canyon over the years. Visitors can hear
the ghosts of Texas history in the
canyon, the Paleo-Indians who arrived
near the end of the Ice Ages, the
Comanches who took control over the
area in the 18th century, and Charles
Goodnight and the early cattlemen who
settled in the area in the 1870s.
Although the canyon area is only a
small section of Texas, the geology along
the route encompasses several interest-
ing facets: the final retreat of the ocean
with the near-extinction of life at the
end of the Permian period, the rebirth of
life in the upper Triassic, the develop-
ment of the extraordinary Ogallala
Formation, and the wind-blown sands
of the most recent two million years
with the amazing fossils found in them.
Taking a Trip through the Canyon
The road trip begins in the town of
Canyon opposite the Plains Panhandle
Historical Museum. The round trip to
the end of the road in the canyon and
returning to the museum is slightly over
40 miles.
The town of Canyon is situated on a
finger of high ground between two
creeks, to the north Palo Duro Creek,
which downstream becomes the Prairie
Dog Town Fork of the Red River, and
one of its tributaries, Tierra Blanca
Creek to the west and south. The high
ground is underlain by deposits of silt,
limestone and loess of the Blackwater
Draw Formation.
South and east of Canyon lies a basin
some nine miles in diameter where the
Blackwater Draw sediments have been
eroded away and the underlying
Ogallala Formation is at the surface.
Forty or more similar large basins are
scattered over the Southern High Plains,
most of them filled with salt water. They
most likely developed as Permian evap-
orite beds dissolved in groundwater,
causing the surface to subside. The near-
est Permian evaporite layer is 860 feet
below the surface at Canyon.
Later, as the valley of the Red River
Prairie Dog Town Fork eroded back to
the north and the Tierra Blanca Creek
valley developed, the lake was drained
and much of the lake bed carried down-
stream. Erosion continued until, at least
in one place, red Trujillo mudstones
26
underlying the Ogallala Formation were
exposed.
Once open to the Red River, several
streams flowed across the basin, deposit-
ing sands, silt and clay, which you can
see today in road cuts around town. At
least two terraces have been cut into the
banks of the basin. The first is about 40
feet above the floodplain of Tierra
Blanca Creek and you climb onto it just
above the Interstate underpass. The sec-
ond, 60 feet above the floodplain, is a
half-mile on towards the park. The ter-
races may have been benches, developed
cent of the recharge of the underlying
Ogallala aquifer in the Southern High
Plains, playas have clay-lined basins and
periodically fill with water from rainfall
and its associated runoff. As water accu-
mulates in playas during rainy periods, it
infiltrates the clay floor through cracks,
plant root openings and other pores and
flows through fissures in the Caprock to
the Ogallala beds below. Eventually,
cracks in the floor swell shut as the clay
itself absorbs water, reducing the
recharge. Once a playa is full, recharge
occurs along its perimeter where there is
A shaded relief map of the Llano Estacado, showing the geologic features of Palo Duro C anyon.
while the lake was still in existence, or
perhaps they developed as the creek bed
deepened.
Playas on the Llano Estacado
Once you reach the High Plains sur-
face at the top of the rise, not much is to
be seen until the road bisects a playa
about two-and-a-half miles beyond
Farm Road 1541. Playas are an interest-
ing feature of the Llano Estacado. Over
20,000 have been mapped, 561 in
Randall County alone; a rough count
west of the canyon found more than one
per square mile. Generally round and
small, they are shallow depressions,
intermittently water-filled, that range in
size from .30 to 843.4 acres, averaging
about 19 acres.
Contributing roughly 85 or 90 per
Cenizo
Second Quarter 2019
little or no clay. In some places where
Blackrock Draw material is thin or
absent, basins have developed in the
Caprock.
There are many theories about the
origins of playa lakes, the most popular
being that they result from wind action
on soils disturbed by drinking animals.
In this hypothesis, rainfall runoff gather-
ing in a low spot on the plain attracts
animals such as buffalo which break up
the soil surface with their hooves. When
the water dries up, the broken surface is
blown away by the prevalent Panhandle
wind. Such saucer-shaped depressions,
called blowouts, are quite common on
the Great Plains. Over time, blowouts
expand to form playas.
Whatever their origin, playa lakes are
important because they store water in a
part of the country that receives as little
as 20 inches of rain a year and has no
permanent rivers or streams. They sup-
port an astounding array of wildlife.
Two million waterfowl winter there, and
you can find mayflies, dragonflies, sala-
manders, bald eagles, endangered
whooping cranes, jackrabbits and rac-
coons at playa lakes. The Eastern
Panhandle is on the Central Flyway, one
of the routes by which birds migrate, so
twice a year, migrating birds use the
playa lakes for water.
Timbercreek Canyon
Timbercreek Canyon comes into
view as the highway dips down to
Sunday Canyon Road. The edge of the
canyon is very close to the highway, so
this is a good place to discuss how
canyons form and the rate at which they
advance.
The walls of these canyons advance
through two main processes. The first
involves spring sapping, seepage erosion
and piping. In spring sapping and seep-
age erosion, water seeping out at the
base of sand beds in the Ogallala, and
sandstone beds in the Trujillo and
Tecovas Formations, carries with it par-
ticles from the beds and erodes them.
Also, because seepage areas are wet,
plants grow there; their roots contribute
to the erosion. In piping, percolating
water creates narrow tunnels or pipes by
physical removal of grains and soluble
material. Pipes exit through the escarp-
ment, sometimes creating large caves.
The second main process involves the
taking into solution of the underground
evaporites. As the salts thin, the surface
above subsides, causing the Caprock to
fracture. Eventually, a body of rock
breaks off from the wall of the canyon
and slumps down the escarpment. Palo
Duro Canyon has many such slump
blocks, although none have been
mapped in Timbercreek Canyon.
A critical question for residents of the
Panhandle is the speed at which the
Caprock Escarpment is retreating. As a
rough estimate, the Ogallala Formation
has been eroded back about 40 miles
from its original eastern boundary in the
last 4.5 million years, slightly more than
one-half inch per year.
The State Park Entrance
The State Park entrance is about 12
miles from the Canyon. A national park
in the upper Palo Duro Canyon was the
dream of local citizens early in the settle-
ment of the area. However, the Federal
government was reluctant to buy park
land from private individuals, rather