Peridotite, which is composed almost entirely of dark silicate minerals and is believed to make up much of earth’s upper mantle, has a composition that is

granitic

ultramafic

andesitic

basaltic

description

The right option is; ultramafic

Peridotite is a dense, coarse-grained plutonic rock that is composed mostly of the minerals olivine and pyroxene. The composition of peridotite is ultramafic, as the rock has less than 45% silica and it has high magnesium content with significant amount of iron. Peridotite is economically valuable because it is a source rock for diamonds, and it is the major constituent of the upper part of the Earth's mantle.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c