Located south of Sprague, Washington, this EarthCache will
introduce you to columnar basalt formations in the channeled
scablands of Eastern Washington. There are no developed hiking
trails and the journey will be about 2 miles roundtrip (parking
coordinates are 47 17.300 N, 117 57.990 W). There are elevation
gains up to 50 feet, but you can skirt around these and pick your
path. You may run into some friendly horses along your trek, as
this is Bureau of Land Management public land - and grazing
livestock is one of the multiple uses here. Wear sturdy hiking
boots and bring plenty of water (especially in the summer time). As
always in the basalt country, keep an eye out for rattlesnakes and
ticks.
More than likely you've heard about columnar basalt and I'm
almost positive you've seen it if while driving from Ritzville to
Spokane on I-90. The world has a fascination with columnar basalt
and some of the most well known and often visited points of
interest are columnar basalt formations. Ever heard of Devils
Postpile near Yosemite National Park, Devils Tower in Wyoming, or
Giant's Causeway in Northern Ireland? All are magnificent examples
of columnar basalt. But little known to the rest of the world,
Eastern Washington's columnar basalt is equally as fascinating.
Take a hike out to this locale and you'll see the columns up close
and personal - and you can walk up the "steps" and catch a nice
view of the scabland country surrounding you.
Columnar Basalt - what is it and how did it form? Basalt is a
volcanic rock, formed from volcanoes or fissures that erupted
molten lava. The basalt near Sprague has a name - the Priest Rapids
Member of the Wanapum basalt, which is turn is a member of the
Columbia River Basalt Group. If you'd like to see the stratigraphic
divisions of the Columbia River Basalts, look
Here.
The basalt in this area originates from ancient eruptions in
Northern Oregon - many miles away. Around 15 million years ago,
viscous lava poured from deep fissures in the earths crust,
flooding the landscape (thus they are sometimes referred to as
"flood basalts"). Eventually the lava cooled into rock and formed
cracks. As the cooling progressed, the cracks became wider and more
pronounced. It's similar to how a mud puddle dries out. At first
the mud puddle is very liquid (viscous) but over time the water
seeps into the ground or evaporates, leaving clay behind. As the
clay dries it contracts, and leaves behind a polygonal pattern.
This is what happened to columnar basalts, they slowly cooled and
dried - from the bottom up - and formed the same type of polygonal
patterns called "columnar jointing". The polygons (or joints) can
be anywhere from 3 to 7 sided as you will see. See
this site for more information.
Learning a bit about the history around Sprague is a part of
this Earthcache too. Originally called Hoodooville, Sprague was
settled in the early railroad and pioneer days of the late 1800s.
The town was incorporated in 1883, five years after the great
Northern Pacific Railroad came through. The town was much bigger
than it is today and rivaled the size of nearby Spokane Falls
(former name of Spokane). If you drive through Sprague, you may
seem some older buildings with basalt foundations and walls. Guess
where that rock came from? Yes, it came from the cache site. But
not only did the pioneers quarry basalt rock from here, they also
came out for scenic horseback rides and weekend picnics. The photo
shown here was taken at the cache site, probably around the turn of
the century.
The coordinates will get you to the south side of the basalt
formation, but take your time and explore around it - climb it,
take pictures, and imagine what it was like here 100 years ago, on
your fine pony. If you were here 2 million years ago, you'd be
underground! The giant Missoula Floods ripped through here over
10,000 years ago, stripping away the soil and huge chunks of rock,
exposing this formation. And, if you were here 15 million years
ago, you'd be swimming in lava and would probably end up like the
Blue Lake Rhino of
Dry Falls (near Coulee City).
To claim this EarthCache, visit the site and take a picture of
yourself with your GPS. Then just email me the answer to the
following two questions:
1. What polygon shape are most of the columns here? (e.g.
rectangular, octagonal)
2. What is the orientation or alignment of the basalt ridge in
azimuth degrees? (Between 0 and 360 degrees, which way does the
basalt ridge point?) You might need a compass if your GPS does not
have a built-in one. Hint: You can also use a topographic map to
estimate the alignment.
Please email me the answers (do not post them here) and
upload your photo to this listing. Hope you have a great time out
there!