The Mogollon Rim was formed during the
Carboniferous and Permian periods. Those periods mark the end of what
they call the Paleozoic Era and lasted from about 358 million years
ago to 252 million years ago.
At that time, there was just one big
continent on the Earth called Pangea. Much of the world was covered
by water. There was a climate change event, and the land dried out
quite a bit. This was when Reptiles evolved from the amphibians and
dominated the planet.
They think that in addition to the
natural change in climate, there was a cataclysmic event. The result
was the largest mass extinction in the history of the planet. 90% of
aquatic creatures and 70% of land animals died out. It was the only
mass extinction of insects that we know of.
Things got crazy. There were volcanoes
and earthquakes and giant space rocks slamming into the planet. There
were huge fires. Rainforests became deserts. Seas dried up. It took
ten million years for life to adapt and recover.
It was one of the dried up seas that left
behind the sandstone deposits of the Mogollon rim. Fossilized
limestone and crystalline bivalves and corals can be easily found.
Some of these corals are the size, shape, and color of a chicken leg.
That's not all the Earth had in store
for building the Mogollon Rim. Beginning about six million years ago,
a chain of volcanoes sprung up in a line across what is now northern
Arizona called the San Francisco Volcano Field. Basaltic lava flowed down over and around parts of the
sandstone plateau. Ash covered it's entirety. The area became
fertile.
Waterways changed again. The last volcano to blow was Sunset Crater about 950 years years ago. The San
Francisco Volcano Field is no longer active. Unlike the volcanoes of
the Pacific Rim, which are products of fault lines, They were the
result of the continental plates moving over a hot spot in the
Earth's magma.The Earth moved on.
The Mogollon Rim Lakes were built in the fifties and sixties for flood management and recreation.
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