Friday, June 11, 2010

Having a Blast in Fort Rock Basin - Part 3, Crack in the Ground



We conclude our brief foray through the Fort Rock Basin with a hike into Crack in the Ground, a 2 mile long fissure running through the desert floor near the edge of the Four Craters Lava Field. Located southeast of the Newbury Caldera, Crack in the Ground is a wonderfully unique formation that is easy to get to and easy to explore.  We were able to hike a lot of it in a short time, but this place definitely merits a return visit of several hours, if not an entire day.


Over time, sand and dirt has blown in to fill the bottom of the crack, leaving behind a rather comfortable trail.
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To wrap your head around Crack in the Ground, it helps to understand that much of this corner of North America was once covered in thick sheets of basalt lava.  The stuff burbled out of calderas and miles-long cracks in the ground for millions of years, slowly building-up and creating thick shelves of the stuff everywhere.  The next time you're driving east of the Cascades, look around you, you'll most likely see remnants of these lava flows resting on top of or sandwiched between layers of ash and soil on in the surrounding hills and buttes.


Wind, water and time have conspired with tectonic forces to reveal some of the Earth's hidden beauty.
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Crack in the Ground is actually a crack in one of these basalt shelves.  It's a fracture that formed in a graben-like structure of basalt nearly 2 miles in diameter produced by several nearby cinder cones on Green Mountain.

"Hold-up, whats a graben?" you ask.

That's a good question. I didn't know either so I looked it up; to really water it down, its a block of sunken earth. In this case, what we're looking at is a basalt shelf that sunk under its own weight into the ground along the edge of a fault-line. The fissure that is Crack in the Ground was formed when the shelf encountered the upthrown end of a concealed fault as it sank; the tremendous tension of this meeting sheered the edge of the shelf off, leaving a nice, wide, easily accessible crack... in the ground.


Chicks still dig geology.
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Primal forces patiently sculpt the rock into an array of amazing shapes and formations.
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This place is really cool, both figuratively and literally; being narrow and deep, the average temperature in the crack is around 30 degrees cooler than that of the surface. Prior to air-conditioning, residents from nearby Christmas Valley would visit Crack in the Ground to escape the summer heat; packing in picnics and making ice-cream from the snow that often goes all year without melting in some of the darker, deeper recesses of the fissure.  With its markedly cooler and moister climate, its not just people that the crack appeals to; an abundance of life prospers there that would otherwise struggle at best to stand a chance on the surface.


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More stress fractures in the basalt hint at the extraordinary forces that were at work here.
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Accessing the trail is a breeze.  Crack in the Ground Road leads north out of Christmas Valley, Oregon to a small parking lot near the north end of the fissure.  Trails from the parking lot lead off to several entrances where the walls have collapsed and eroded away over time, leaving behind ramps of debris leading down into the breach.  The nearest entrance actually seemed to be the least accessible; the north side of it is all but blocked off by rubble and the south side only goes so-far before encountering a steep drop that will prohibit a lot of folks from continuing.  However, if memory serves, the rest of the trail should be near universally accessible from the southern end, you just gotta walk the length of the crack on the surface to get there first. I want to say that the southern end of the trail is even wide and smooth enough for wheel-chairs but I honestly don't remember the trail conditions leading to that point although it didn't seem taxing.


One of the entrances, partially obscured by Junipers and scrub brush.
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Naturally occurring dividers and windows dot the length of the fissure.
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All-in-all, the trek through the desert to Crack in the Ground was very-much worth the time and effort. Its a friendly hike through a fascinating natural phenomenon that is rarely seen on our planet.  While stress fractures like Crack in the Ground are not uncommon, one that hasn't been completely filled-in and covered over with sediment and debris is actually quite unique.  I eagerly await my next opportunity to photograph this sensational structure.


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