2. Fender BenderThis theory was off

2. Fender Bender
This theory was offered in 1981 by Julie Maxson and Basil Tikoffrom the
University of Minnesota. In the early 1980's accretion was first recognized as a major
component of plate tectonics. Researchersealized that continents grew along subduction
margins as sea floor was scraped from the subducting plate onto the edge of the continent.
With this new discovery came a new idea as to why the Rocky Mountains formed.
In this theorv the Rockies formation is attributed to a miniature continent that smashed
into the west coast'of the United States about 90 million years ago. This theoretical
continent was too smallto generate a large scale collision like the one we see in Asia that
uplifted the Himalayas, but it was large enough to deform the entire western poftion of the
North American continent. Since the continent was small, it did not cause a massive collision
event but rather a smaller collision that resulted in a brief, but vigorous,uplift some 80 million
years ago.
This theory, like the first one proposed above, has endured the test of time. After a
decade of scrutiny it is still accepted by a number of geologists. Remnants of the
proposed microcontinent can be found throughout the western portions of North America.
The region to the west of the Rockies provides lots of evidence that support a collision
theory. Various exotic plants are found in Southern Oregon and Northern California. The
distribution of these plants can best be explained by having them evolve on a separate
continent in the Pacific Ocean. These plants then became part of the Nofth American
continent as a result of the collision described above.
ln addition to the fossil evidence on the sudace of the continent, this theory is also
suppofied by the structure of the Rocky Mountains. Many of the ranges that make up the
Rocky Mountains appear to have similar characteristics to mountains uplifted by the process
of collision. lf Norlh America did collide with a smaller continent located in the Pacific Ocean, it
is reasonable to believe that mountains like the Rockies would form.
Despite a quantity of evidence supporting this theory, it is still questioned by many
geologists. One large problem with this theory is it fails to explain the various regions of
volcanism located within the Rocky Mountains, The Southern part of Colorado and much of
New Mexico display regions of abundant volcanic activity. The collision theory cannot
explain this and is, therefore, rejected by many geologist