Thursday, May 9, 2013

South Valley Park and the Future



            South Valley Park open space is a unique geographic region.  The hogback ridge is an anticline, the valley a syncline, and the foothills rising to the west a monocline.  The hogback was formed hundreds of millions years ago, during the Jurassic and Cretaceous periods, due to tectonic forces pushing up the sandstone rocks of the Dakota Group.  The final upthrusting was the Laramide Orogeny, beginning 70 million years ago, and probably caused by the North American plate slamming into the northeast-moving Pacific Plate.  The Laramide uplifts rose up vertically as narrow, north-south upfolds (anticlines), elevating the formerly flat layers of sedimentary rock in a series of wave-like ripples.  Most of this sedimentary rock has eroded, their broken ends forming the hogback escarpment.  These sandstone features are porous and permeable; the clastic sediments were formed in a subtropical climate, when a shallow ocean covered the land.  Today, the environment of South Valley Park is deeply shaped by the drought conditions that affect the entire state of Colorado. 
1,000 years from now, South Valley Park will look very much like Utah: red, treeless, nearly grassless.  Global temperatures are expected to rise dramatically in the next hundred years.  The melting polar ice caps and methane escaping from the tundra permafrost will create a positive feedback cycle that will make much of the world, including South Valley Park, uninhabitable by mammals.  Geologically speaking, South Valley park will look much the same.  Rock decay and chemical weathering will continue to wear down the intrusive sandstone boulders, but not so much that changes are visible to the naked eye.  What will change is the vegetation; greasewood will replace the mountain mahogany and sagebrush.  The water table will continue to drop, and even seasonal spring streams and marsh regions will disappear. 
10,000 years from now, South Valley Park will again be carpeted with short-grass prairie, rich summer marshes, seasonal river floods, and the few small mammals that survived the Anthropocene Mass Extinction Event.  There will be no human presence affecting the hogback, because humans will be extinct, the last few families dying thousands of years earlier while attempting to farm in Siberia and Alaska.  Global warming, by now, has burned itself out, and an intensifying Ice Age has swung global temperatures back to what they were during the Last Glacial Maximum.  The region will still be characterized by aridity, but instead of the dramatic seasonal temperature differences of the Holocene, the climate is more like it was during the Pleistocene; the aggregate temperature, that is, will be several degrees colder than today, but there will be less seasonal variation.  Also, landscapes will not be striped as it today, but a mosaic of interlinked habitats.  This means that wild horses and elk will exist side by side with musk oxen.    
1,000,000 years from now, South Valley Park will not exist in its present form at all.  Due to renewed tectonic uplifting and a long balmy interglacial, the current valley will be an enormous, Everest-sized mountain encircled by a shallow semi-tropical lake.  A new type of animal -- neither lizard nor mammal -- will frolic in the marshes and the forests mountain slopes.  As in the ancient past, the lowland areas will be covered with confers, eucalyptus, magnolia, and fig trees.  Oak, walnut, and ash will flourish in the upper montane.     

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