What's an Earthcache?
It's a hunt in which knowledge is the prize!
Now, to get started...
Redbud Valley Nature Preserve was the first property in Oklahoma to
be purchased by the Nature Conservancy. There are no endangered
species being preserved here. It is only a little over 200 acres.
So what's so special about it? In one word: diversity.
Because of the underlying rocks, and the way water flows over,
around, and through them, there are a great variety of habitats in
a very small area. The one-mile trail wanders through places that
resemble the flat, dry, sunny upland prairies and forests of
central Oklahoma's Cross Timbers. It also climbs through a shady,
damp, steep-sided valley that would be at home in the Ozark
Mountains. Tarantulas and cactus live less than half a mile from
salamanders and ferns! Those are only the two most extreme
examples. It's like a patchwork quilt of many small ecological
zones, with different amounts of sunlight, water, soil, and wind in
each one.
There are geological stories everywhere at Redbud Valley Nature
Preserve. You might want to print this out to take with you on your
walk around the trail. You can use it as a checklist, to make sure
you find it all!
___ Watch for fossils of sea creatures in the rocks under
your feet as you climb the steps. The Oologah Limestone, a.k.a.
"Big Lime", is known for its abundance of brachiopods, crinoids,
and horn corals. The rock quarry to the south is mining Big Lime,
mostly to use as a component in cement production. Collecting is
not permitted in the preserve, but you may pick up a brochure at
the visitor center that lists several public locations where you
may find fossils to take home.
___ The Oologah Limestone holds together well, forming big massive
cliffs and bluffs. But water trickles through the pores of
the limestone like water through the holes in a sponge. Unlike a
sponge, however, the limestone is dissolved by the water, and the
holes get bigger as more and more water flows through them. A
visible hole in the rock is called a vug, and a bigger one is
called a cave. When the ceiling of a vug or a cave collapses or
dissolves, it is called a sinkhole. The trail will take you past
vugs and caves. One cave is big enough to crawl into, so you
may want to bring a flashlight. The cave is closed during the
winter, to protect hibernating bats.
___ Bird Creek on the north and Redbud Creek to the east have
eroded long trenches in the Oologah Limestone and cut down into the
layers of rock beneath, leaving hills on either side capped with
ledges of limestone. The Oologah Limestone is strong, but has a
series of cracks. Rainwater finds its way into those cracks and
widens them. If the water freezes, it expands and acts like a
wedge, widening the crack even more.
Eventually the edges split off in large chunks, called slump
blocks. The main trail goes up among a group of slump blocks
and then down again through another group. The bluff trail meanders
along the lower edge of slump blocks in the process of breaking
away. The blocks you see on the slopes are sliding down the hill
very, very slowly. The main trail's boardwalk will take you to a
bench beside a slump block that tipped onto its side as it came
down.
___ Underneath the limestone is the Labette Shale. Shale is
impermeable, meaning water does not flow through it very well. At
the point where limestone meets shale, the water that has been
seeping through the limestone cannot go down through the rock any
more. If that contact point is on the side of a hill, that is where
the groundwater comes out as seeps and springs. (NOTE:
UNTREATED SPRINGWATER IS NOT SAFE TO DRINK.)
___ Shale is much more crumbly than the limestone, so water and
wind eat away at it much faster. All kinds of animals find shelter
in the places where the shale has eroded leaving limestone
overhangs. Look for the shallow pits of antlion larvae, called
"doodlebugs." (NOTE: A ROCK OVERHANG IS NOT A SAFE PLACE TO WAIT
OUT A THUNDERSTORM. LIGHTNING CAN STRIKE FROM THE CEILING TO THE
FLOOR OF THE OVERHANG.)
___ Shale crumbles into new soil much faster than
limestone. Along the upland prairie trail, the rocky soil is very
thin. Below the bluffs the soil is much more abundant, but the
slopes are unstable, and life there is very fragile. Most of the
new soil slides down the steep slope to the flat terrace below.
(PLEASE REMEMBER TO STAY ON THE TRAIL TO PROTECT THE FRAGILE
ECOLOGY OF THE SLOPES.)
____ The soil in the terraces along Bird Creek is growing
deeper for two reasons. It is sliding down from the slopes above,
and Bird Creek is bringing sand and silt from Osage and Tulsa
Counties. Every flood piles another extra deep layer on top of the
routine daily deposits. At one point along the main trail, at the
east end of the boardwalk, you can look across Bird Creek for a
good view of the steep earthen banks. You can also see soil
swirling along in the brown water of Bird Creek.
___ Bonus: Sometimes after a hard rain, small bits of chipped
flint appear along the trail under the bluffs. The flint did not
form here. It was brought to this location by people who used it to
make stone tools. The tiny fragments of worked stone
indicate a place someone sat to make tools, thousands of years ago.
It's not hard to find reasons why a stone-age craftsperson would
have carried tools and chunks of flint to this place to live and
work.
To log this Earthcache:
First, come inside the visitor center to study the model that
shows how the geology affects what lives on the surface. Make note
of the three types of living creatures depicted in the model, to
show scale. If you don't have a kit with a thermometer, measuring
tape, and wind speed scale, you can probably borrow one here,
unless someone else has it checked out.
Second, hike the one-mile loop, being sure to include the main
trail and its boardwalk along Bird Creek, as well as the prairie
trail near the barbed wire fence that indicates the property's
original south boundary.
Third, when you come to the bench along the boardwalk, and when
you come to the barbed wire fence along the prairie trail, stop and
measure these four items:
1) the temperature (which site was warmer?)
2) the wind speed (which site was windier?)
3) the average height of the closest trees (which site had taller
trees?)
4) the percentage of sky unblocked by tree cover (which site had
the most open sky?)
Finally, send us an email at oxley@ci.tulsa.ok.us Tell us:
1) what the three creatures in the model are (be sure not to
mention them in your log, please,)
2) how the two locations along the trail compared,
3) how many people there were in your party, and
4) the date you visited.
You do not have to wait for us to answer your email before you
claim this waymark, but we will delete logs from visitors who did
not send an email. It would be good if your log mentioned any signs
of wildlife you might have found, as well as any insects, spiders,
reptiles, amphibians, birds, mammals or other animals you actually
met along the trail. At the visitor center, you can also pick up
the second set of coordinates for the multi-cache "Redbud
Rocks."