Deposits of the
Payson Basin can be easily seen along Highway 89 on either side
of the turn off to Roosevelt lake in the roadcuts and along the
sides of the road as light colored limestone, and siltstones.
Although fossils are few along the highway, other areas of the
basin have produced Pliocene Pliohippus horse teeth, plant hash
such as reed and aquatic plant impressions, worm burrows and
small turriculate form gastropods. Taylor in his report on Blancan
mollusks in the western United States mentions identifies the
gastropod species as Lymnaea, Promenetus, and Physa. Pollen analysis
of the sediments found in the Basin indicate that the Pliocene
climate was a woodland-savanna community, dominated by pine.
In the Payson Basin
the lacustrine sediments include a fairly high proportion of
sand and pebbles. Some of the beds are buff to light rusty red,
but the prevailing colors are light creamy yellow to white, similar
to the beds in the Verde and San Carlos Basins.
Six mappable units
are recognized within the Payson Basin according to Pedersen:
Undifferentiated bedrock, Older alluvium, Fine grained alluvium,
Coarse grained basin fill alluvium, Terrace alluviums, and Floodplain
alluvium. Below you will find images of our exploration of the
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BELOW FOR AN ENLARGED VIEW
Typical scene in
the Payson basin. The Mazatzals mountains are in the distance,
and in the foreground the lowlands contain alluvium, shales,
sandstones, and limestones of the Payson Basin formation. The
butte off to the right is Table Mountain, which has a sandstone
cap from the Payson Basin formation. This view from near Rye.
Parked along the
road in Rye, the white limestones of the Payson Basin formation
cover the road in roadcuts. Some are highly fossiliferous, and
contain abundant gastropod fauna. Also found at this site, were
ostracods, plant hash, and mummified roots.
This piece of white
dolomite, contains hundreds of small coiled gastropods, all of
one species. All of the freshwater gastropods found in the Payson
basin are usually under a quarter inch or less in size. Occasionally,
there are larger specimens to be had.
One of the largest
gastropods we found that was a turriculate form type, was this
one in a tan dolomite. Excellent detail can often be preserved
in the dolomites, including the growth lines and protoconch detail.
This peculiar looking
fossil, is a fossil cattail reed in the center, surrounded by
a ring or spiral arrangement of small gastropods all of the same
size around the base of the reed. This is an example of the snails
laying thier eggs on the stem of the cattail, and some period
after they hatch many of them fall to the bottom in a circular
pattern. In this case, they were quickly buried by some sort
of event, and preserved.
Many of the gastropods
found in the Payson basin such as this one found South of Rye,
still have a white calcified material lining the shell cavity.
This is the remains of the aragonitic shell preserved in the
reed, with growth lines along its length. Many of the boulders
and rocks found in the region contain the tubes of cattails and
aquatic plants. This indicates a nearshore condition in only
a few inches of water.
Typical plant hash
found in great abundance in the Payson basin formation. The partially
macerated remains of reeds, grasses, and aquatic plants can be
found in great layers throughout the formation. This example
here shows many small bits in some limestone found on the north
and of the Payson basin.
Very fine rhizomes
in a nearshore environment created by either aquatic, or or plants
that grew just out of the water. The small tubes represent the
passages in which the the feeding tendril roots of plants searched
through the sediment for water. Occasionally, as we have found
in certain areas,some of the larger root tubes contained modified
remains of the original roots still intact. Such preservation
is rare and outstanding, and uses a glimpse of the ancient root
structures which created the tubes.
More typical rhizomes
are the larger type, which span up to an eighth inch in diameter.
They are less packed than the fine hairlike rhizomes as seen
above, and represents more larger root structures probing for
This large block
of limestone found in a creek, is filled with giant rhizomes.
It almost looks like Swiss cheese because of the large number
of tubes contained within.
Root Mummies. This
60x view shows the contents of one of the rhizomes we found,
that was deep inside a giant boulder and shows the modified remains
of the rhizomes progenitor. Although they have shrunk down considerably
to a smaller size, they were quite abundant in some areas deep
within the insides of the rocks.
A better view of
another root mummy, which has shrunk to about a quarter the size
or less of the original rhizome cavity. Higher magnifications
revealed an extremely strange appearance which was withered,
and twisted. We have never seen anything like this before, and
plan to pursue this further in our outings.