American Heritage® Dictionary of the English Language, Fourth Edition
- adj. Containing magnesium and iron and only a very small amount of silica. Used of igneous rock.
Century Dictionary and Cyclopedia
- In petrography, extremely rich in the base-forming elements and poor in silica: applied by Judd (1881) to peridotites, hornblendites, limburgites, and related igneous rocks.
- adj. geology ultramafic
“The higher elevations of the Nicobars often contain serpentine and gabbro formations, whereas at lower elevations Eocene sediments (sandstones, shales, and siltstones) with ultrabasic igneous intrusions predominate.”
“Metamorphic schist, limestone, ultrabasic rocks, and volcanic rocks are the main parent rock formations of the ecoregion.”
“This ecoregion also contains patches of ultrabasic rocks.”
“Mesozoic dolomite and limestone predominate; other important substrates are sandstone and marl, the oldest crystalline metamorphic (i.e. quartzite and schist), and ultrabasic serpentines (Smolikas range).”
“Goodenough, Fergusson, and Normanby islands consist mainly of lowland rain forest on acid soil; however, Normanby has one area of ultrabasic soils.”
“The ultrabasic soils of Normanby have turned up exciting new finds, including two endemic ant-plant species.”
“Grande Terre island is one of the most biodiverse islands for this taxonomic group, with species found only in ultrabasic substrata and others only in some short, oxygenated rivers of the north.”
“This rich biodiversity and high endemism are due to its long-isolated evolution, as well as the variety of precipitation levels and very particular ultrabasic soils that cover more than one third of the country.”
“East and West Sulawesi collided approximately 13-19 million years ago, and ultrabasic rocks were exposed as East Sulawesi overrode the western portion.”
“The higher elevations of the Andamans often contain serpentine and gabbro formations, and at lower elevations Eocene sediments (sandstones, shales, and siltstones) with ultrabasic igneous intrusions predominate.”
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