Mafic The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older "basic rock" class. Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions. Most mafic-lava volcanoes are shield volcanoes, like those in Hawaii. Mafic Mafic is an adjective describing a silicate mineral or igneous rock that is rich in
Ogeechee River the Atlantic Ocean. From a shallow clear running stream with several shoals, rapids, and a small falls at Shoals, below Louisville the river becomes a lazy meandering channel through cypress swamps and miles of undeveloped forests. The Ogeechee River basin contains parts of the Piedmont and Coastal Plain physiographic provinces, which extend throughout the southeastern United States. This boundary follows the contact between older crystalline metamorphic rocks of the Piedmont Province and the younger unconsolidated Cretaceous and Tertiary sediments of the Coastal Plain Province. Other rock types found in the basin include metasedimentary rock, schists and phyllites, felsic and mafic