Synthesis of late Paleozoic and Mesozoic eolian deposits of the ...

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Blakey (1986) documented the presence of small
eolian dunes and sabkha and/or wet interdune
deposits for this facies.
The Coconino Sandstone formed downwind
from eroding eolian and marine rocks to the north.
Reworked eolian sand moved southward across
the featureless terrain of central and northern
Utah until it encountered an area of subsidence
associated with the last stages of the Holbrook
Basin. Some areas in the Mogollon Rim were close
enough to marine areas to the south to form
interbedded sabkha and coastal dune deposits.
However, most of the Coconino and at least some
of the Glorieta were deposited in an inland erg far
removed from direct marine influence as shown by
a dominance of deposits formed by large dunes
with few wet interdune deposits.
Leonardian 111 eolian deposits
The latest Leonardian ergs, possibly partially
Guadalupian in age occur in widely separated
areas of the Colorado Plateau and north-central
Colorado. Correlation of these two eolian com-
plexes is considered somewhat tentative but is
based on relations with adjacent marine rocks and
regional correlation as shown by Rascoe and Baars
(1972). The White Rim Sandstone and upper
Coconino Sandstone form the western erg deposits
and the Lyons Sandstone forms the eastern one
(Fig. 11). Eolian deposits have also recently been
identified to the east in the Leonardian and
Guadalupian of west Texas and adjacent New
Mexico (Nance, this volume). At present it is
uncertain as to how these deposits related to the
major erg systems to the west. The Lyons Sand-
stone was carefully documented to be of eolian
origin by Walker and Harms (1972). Stratigraphic
relations were provided by Thompson (1959) and
Hoyt (1963). The Lyons forms a parabolic-shaped
deposit in which the trough of the parabola trends
east-northeast (Fig. 11). The center of the unit is
about 60 m thick. To the north the Lyons inter-
tongues with marine carbonate and sabkha red-
beds of the Owl Canyon and Satanka Formations
(Figs. 2 and 7B). Eastward and southeastward it
grades into marine carbonates and redbeds and
southwestward it intertongues with the upper
Fountain Formation. The west edge of the
parabola is truncated by the present-day Front
Range, though it seems probable that the Lyons
once extended several tends of kilometers west
across the edge of the Ancestral Front Range.
The White Rim and upper Coconino Sandstone
complex is confined to the west of the Sedona and
Monument Arches and extends from central Utah
to the Mogollon Rim in Arizona. Sedimentologic
data are provided by Baars and Seager (1970),
Rawson and Turner-Peterson (1980), and Kamola
and Chan (this volume). Stratigraphic data are
provided by Irwin (1976) as well as the above
authors. The eastern feather edge of the White
Rim follows the present course of the Colorado
River southward into Arizona; however, in Arizona
the upper Coconino extends eastward to an area
across the Sedona Arch where it can no longer be
separated from the lower Coconino and is there-
fore included with it on Fig. 10. The White Rim
Sandstone averages about 60 m in thickness across
much of its extent but thickens to over 250 m in
the Circle Cliffs trough (Figs. 7D and 10). Baars
and Seager (1970) pointed out that the eastern
margin is not a true feather edge but rather the
unit thins to less than 10 m and grades eastward
into redbeds of the Organ Rock Formation. In
some areas this edge has been modified by pre-
Triassic erosion. The White Rim and upper
Coconino everywhere grade westward through a
zone of complex facies change into marine
carbonate and sabkha evaporite and sandstone of
the Toroweap Formation (Fig. 7D and E). This
change is well documented by Irwin (1976) and
Rawson and Turner-Peterson (1980). The facies
change follows the west edge of the Sedona Arch
from the Mogollon Rim northward to near Page,
Arizona and then swings northwestward along the
Kaibab Arch; then it swings back to the northeast
near and parallel to the west edge of the Colorado
Plateau (Fig. 11). The White Rim Sandstone is
truncated by erosion along the northwest-trending
Emery Arch in central Utah (Rascoe and Baars,
1972; Irwin, 1976).
We have field-checked some of the reports of
intertonguing of the White Rim and upper
Coconino with the overlying Kaibab Formation.
In areas that we have field checked, we have not