Absolute age is the age of a geologic formation in years. Unlike relative age, which determines whether a formation is older or younger than its surrounding formations, absolute age provides geologists with the actual age of a formation.
The absolute age is determined by a number of dating techniques:
Felsic, intermediate and mafic igneous rocks differ in their mineral composition. Felsic rocks are light in color and are composed of feldspars and silicates. Mafic rocks are darker and are composed of magnesium and iron. Intermediate rocks are composed of the minerals amphibole and feldspar and contain a combination of light and dark minerals.Full Answer >
An ice cap is a glacier that covers less than 19,000 square miles. These miniature ice sheets form in polar and subpolar regions that are high in elevation and possess a relatively flat surface. Glacial ice that covers an area greater than 19,000 miles is known as an ice sheet.Full Answer >
According to geography professor Muncel Chang on About.com, water can float on water if the two types of waters have different densities. Fresh water, for example, has a lower density than salt water, and therefore it floats atop salt water.Full Answer >
Wind blows due to air-pressure gradients that are the result of the uneven heating of the Earth's atmosphere. Prevailing winds blow in a consistent direction over large areas of the Earth's surface, while local winds are dependent upon regional geography.Full Answer >