Roatán, (16.34°N 86.33° W) lays across the Cayman Trench at the northwestern intersection between the Caribbean and North American Plates.
Image Credit: Purdue UniversityThe easiest way to describe Roatán's formation is to say that through a process of transforming plate interaction and a parallel process of divergence between the North American Plate and Caribbean plate, magma was allowed to escape from below the earth's crust. The transform process allowed the sub-aquatic magma to cool (through an exothermic process) and form the resultant igneous rock - which eventually ended up forming the Bonacca Ridge, which resides underneath the Bay Islands, and more importantly: Roatán.
Because magma was moving from an area of high pressure to low pressure, magma moved through dikes to reach the ocean floor, and the basalt lava flows allowed centuries of compiling igneous rock to eventually form the ridge islands.
It would not be completely absurd to assume that a process of extension faulting allowed some of the material of the ridge to move in certain ways that effect its height (which would account for the fact that pats of the island are at a higher elevation than others).
Areas where the plates were convergently moving created areas of anticline folds.
Sources Consulted:
Because magma was moving from an area of high pressure to low pressure, magma moved through dikes to reach the ocean floor, and the basalt lava flows allowed centuries of compiling igneous rock to eventually form the ridge islands.
It would not be completely absurd to assume that a process of extension faulting allowed some of the material of the ridge to move in certain ways that effect its height (which would account for the fact that pats of the island are at a higher elevation than others).
Areas where the plates were convergently moving created areas of anticline folds.
Interesting Look at the trough surrounding Roatán and the Bonacca Ridge, Courtesy: Stanley Submarines
Sources Consulted:
"Island Geography." Tourism Roatan. Web. 14 Feb. 2011. http://tourismroatan.com/about-roatan/geography
Mann, Paul. Geologic and Tectonic Development of the Carribean Plate Boundary in Northern Central America. Boulder, Colo: Geological Society of America, 2007. Print.
http://books.google.com/books?id=CvmNCC0W97wC&pg=PA52&lpg=PA52&dq=bonacca+ridge+formation+site&source=bl&ots=jyciKoT7y-&sig=bXI8l-tB3FU2SjqQ9dCAzgFLuv8&hl=en&ei=rf9aTaSmB4r6sAPz_9COCg&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBMQ6AEwAA#v=onepage&q&f=false
http://books.google.com/books?id=CvmNCC0W97wC&pg=PA52&lpg=PA52&dq=bonacca+ridge+formation+site&source=bl&ots=jyciKoT7y-&sig=bXI8l-tB3FU2SjqQ9dCAzgFLuv8&hl=en&ei=rf9aTaSmB4r6sAPz_9COCg&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBMQ6AEwAA#v=onepage&q&f=false
Rogers, Robert. "Chapter Two Figures." Geology at CSU Stanislaus.
Web. 14 Feb. 2011. http://geology.csustan.edu/rrogers/Rogers2003/chpt2_figs.htm
Web. 14 Feb. 2011. http://geology.csustan.edu/rrogers/Rogers2003/chpt2_figs.htm
