Bibliografía páginas 31-33

Puerto Rico is the eastern-most acd smallest of the Greater Antilles and is situated between 18°31’ and 17°55' N latitude and 65°37’ and 67°17' W longitude. The main island, about 160 kilometers long and 55 kilometers wide, occupies about 8,900 square kilometers including the offshore islands of Vieques, Culebra and Mona. The small mountainous island, lying directly in the path of the easterly tradewinds, shows a remarkable diversity in its physical environment (Pico 1974). The interrelations of local geology, physiography, climate, and soils influence the structure and composition of the forests. Nearly all forest areas have also been heavily influenced by man. The geologic history of Puerto Rico began more than 100 million years ago during the Cretaceous period. A geosyncline elongated through the Antillean region, and active volcanism occurred until near the end of the Middle Eocene epoch, giving rise to predominantly submarine accumulations of volcanic rocks (Beinroth 1969). Limestones originated along with tuffaceous shales at this time. Extensive faulting and folding then occurred, accompanied by the emerging plutonic rocks which are now found in the vicinity of San Lorenzo and Utuado. The serpentine found in southwestern Puerto Rico probably intruded during the Cretaceous period. Later during the Middle Oligocene to Middle Miocene epochs, younger Tertiary limestones were formed. Slight uplift and tilting followed, about 15 million years ago.