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Pink dotted lines -- Anticlines
Black dotted line -- Stockton Fault
Source: California Dep. of Conservation
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These folds likely exist because of the tectonic plate activity next
door in the bay area. These geographic forms occur because of compression. This
compression comes from the extensive amount of movement and plate activity to
the west. The fold to the south, right beside Stockton, possibly resulted from
compression when the close-by Stockton Fault came into existence. The formation
of reverse faults wherein the hanging wall pushes upward relative to the foot
wall (source), like that of Stockton (source), requires the
same compression as anticlinal folds.
Information on the Stockton Fault turned out to be extremely
scarce. So, based on current knowledge from this introduction to Physical
Geography class, I am going to take a crack at guessing what type of process
created it:
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A safe hypothesis as to what caused this compression which
resulted in the fault and folds begins with an earthquake. Some thousands or
millions of years ago, the North American and Pacific plates caught one another
during their strike-slip process building up immense pressure over time.
Eventually, they jolted past each other with extreme force. This exertion of
force caused an earthquake of epic proportions that radiated across the bay
area all the way to the present day Stockton region. Here, the more plastic
land (Thornton and Stockton Arches) folded upon itself, rather than breaking
(a.k.a. faulting) like the Stockton Fault.
