Sunday, December 9, 2018

Week 7 - Death Valley Field Trip





















  



Badwater salt pan
Photo credit:  USGS

The Badwater stop shows large salt flats in its image gallery.  I have to wonder about the source of all this salt.  Perhaps a geologic map could tell me the types of rocks that lead to this basin.  The nearly pure sodium chloride supersedes all other minerals so could volcanic activity have created such high heat that mostly only recrystallization of sodium chloride remained?
 


















Furnace Creek alluvial fan
Photo credit:  USGS

The alluvial fans seen from photos at the Furnace Creek stop show multiple layers of deposited sediment.  Drilling a core sample in this area would answer my question of whether there is still water flowing in this area forming these alluvial fans or whether these fans are left over from long ago stream flow.  Alluvial fans often have water trapped in depths of soil that cannot seep past an impermeable layer.  Water levels are replenished from subsequent rainfall.  Core samples showing moisture would indicate that these alluvial fans are still a channel for stream flow and water has not eroded a new path to some other area of the desert.

















Saratoga Springs marsh pond
Photo Credit:  USGS


A photo from the Saratoga Springs stop on the tour shows one of three marshlands within the desert park.  It is said that these ponds are fed by multiple springs.  It would be interesting to know the continual source of these springs that feed these ponds such as is represented at Saratoga Springs.  Would water analysis of the feeder springs yield mineral content that matches a certain type of rock such as igneous, sedimentary, or metamorphic rocks specific to a certain layer in the bedrock and thus tell me whether these springs are more surface related in origin or come from a deeper aquifer?  A geologic map may tell me whether there were faults or volcanoes giving clues to rock types to be expected.

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