The first stake is some distance along the trail, so keep walking and
watch for it.
1. The cave-like depressions in the side of the rock are created by
water. Rain falling on the top of the mesa enters cracks in the rock,
runs down the cracks (called joints), and comes out of small openings on
the side of the mesa. The water seeping out of the opening gradually
wears away the rock. The freezing of the water in winter and thawing in
summer helps to weaken the sandstone.
The tall trees in the vicinity of this stake are ponderosa pine (_Pinus
ponderosa_). They are readily identified by the needles, which grow two
or three to a cluster. These trees grow in well-watered, protected areas
within the Monument. The larger ones are somewhere between 200 and 300
years old.
2. Here you can stop and catch your breath before beginning the steep
climb. Look at the top of the mesa, to your right, just below the
railing. You can see very clearly two different formations of rock. The
lower is the sandstone called Zuñi formation and the higher is the
Dakota formation. The line between these two formations represents a
time interval of between 25 and 30 million years. More about this later.
Behind the numbered stake near the base of the rock, you will see a
Gambel oak (_Quercus gambelii_). It is commonly associated with
ponderosa pine and is the most abundant oak of the low mountains and
plateaus of the Southwest. It is characterized by its deeply-lobed
leaves, and its habit of growth. It ranges from a shrub to a tree in
size, and is often seen in dense stands, which give it the name of
“scrub” oak in certain localities. Deer and livestock browse this tree,
and small animals use its acorns for food.
3. The policy of the National Park Service is to keep the parks
looking as natural as possible. Since it is natural for dead trees to be
in a forest the ones you see in this area will not be cleaned up. When a
tree falls in a National Park Service area it will lie where it fell and
eventually will decay and supply nourishment for future trees.
4. Take a break here and look at the valley between the multicolored
mesa and the higher parts of the Zuñi Mountains. This valley was formed
by water gradually wearing away the softer rocks of the Chinle
formation. The harder sandstones of El Morro and the adjacent mesa on
the southwest and the sandstones and limestones of the higher slopes
resisted such erosion.
During the last few million years, while the Zuñi Mountains were being
gradually pushed up to their present height, more than 10,000 feet of
sedimentary rocks have been removed from what you see. This has been
done by running water and wind, carrying away the rocks a few particles
at a time. Before that, about 100 million years ago, this entire area,
as far as you can see in any direction, was under the water of an
ancient ocean. Forty million years before that, the sands of El Morro
were accumulating on a broad, desert-like plain, built up by sand
deposition of sluggish, wandering streams, and re-sorted by wind into
large dunes.
Before continuing along the trail, you will notice many small trees
around you which are called pinyon (_Pinus edulis_). These pine trees
have two needles to a cluster and are never tall like the ponderosa
pine. They are usually less than 35 feet in height, and have a rounded,
compact crown. Pinyons are seldom found growing in pure stands but are
associated with various kinds of juniper. Because of the nature of their
growth, heavy stands of pinyon and juniper are often called pigmy
forests. The pinyon produces edible nuts which are abundantly used by
local residents as well as marketed commercially elsewhere in the United
States.
5. Here you can see at close hand the difference between the dark,
upper layers of ocean sands and the light color of the lower and earlier
stream and dune sands. Look here at the cliff above you and a little to
the right. The lower is Zuñi sandstone, of the Jurassic period, and
forms the bulk of El Morro. The upper is Dakota sandstone of Cretaceous
period, representing beach deposits of the ancient sea which covered all
the area. The contact surface between these two units represents a time
interval of between 25 and 50 million years when erosion instead of new
deposition was taking place.
6. Look on the left side of the trail and a little behind you. You
will see a dark green stake that marks one of the four corners of the
unexcavated ruin. Let your eye follow along the top of the incline to
your right and you will see another green stake, another corner. As you
follow the trail on this side of the box canyon, look to your left for
the last two stakes and you can tell how big this ruin is. Please do not
leave the trail.
This village was possibly two or three stories high, but after the
Indians left, the roofs collapsed and the walls fell in. Then the sand
blew in, weeds began to grow, and you see the result.
7. Looking at the cliff wall across this little box canyon, you can
see a definite horizontal line about half way down. The materials above
and below the line were laid down about the same time, but the line
represents a layer of softer material which has weathered away faster.
The reason for the unevenness is that stream channels cut into the
underlying sandstone, and then, as the land slowly settled to allow the
sea to encroach, the channels filled up with sand. The sands were
reworked by waves on the beach and the tops smoothed out and leveled.
Small lagoons and swampy areas formed along the coastline. As you climb
the steps at No. 11, you will cross a small seam of coal-like material
which was formed from one of these swamps.
[Illustration: _The geological disconformity described at Stake 7._]
If you look across the box canyon, on the horizon you will see the ruins
of another village. It was occupied about the same time as the one on
this side of the mesa.
Across the top of the mesa, the trail will be marked with two parallel
lines. Please stay between the lines.