ScienceIQ.com

What Causes Ice Ages....Or Global Warming?

We know from the rock record and cores taken from polar ice caps that periods of global cooling (ice ages, or periods of glaciation) have alternated with warmer, more temperate periods having climates similar to what we now experience (interglacial periods). Graphs of the change in earth's average surface temperature over geologic time indicate ...

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IceAgesGlobalWarming
Biology

What Elements Are Required By Animals And Plants For Survival?

An understanding of our fragile environment can begin with a recognition of the importance of certain elements, commonly called 'mineral substances' (such as iron and zinc), in the lives of humans and ... Continue reading

AnimalsPlantsSurvival
Physics

How Fast is Mach 1?

A Mach number is a common ratio unit of speed when one is talking about aircrafts. By definition, the Mach number is a ratio of the speed of a body (aircraft) to the speed of sound in the undisturbed ... Continue reading

Mach1
Mathematics

How To Calculate The Circumference Of A Circle

A circle is what you get if you take a straight line and bend it around so that its ends touch. You can demonstrate this by taking a piece of stiff wire and doing just that: bring the ends of the wire ... Continue reading

CircumferenceOfACircle
Engineering

The Motion of An Aircraft

We live in a world that is defined by three spatial dimensions and one time dimension. Objects move within this domain in two ways. An object translates, or changes location, from one point to ... Continue reading

TheMotionofAnAircraft

Metamorphic Rock

MetamorphicRockThere are three rock types on earth, named according to how the rock is formed. Igneous rock forms as it cools to a solid from molten rock. Sedimentary rock is formed from the consolidation of particles that come from other rock that has been weathered and eroded. Metamorphic rock forms when solid rock is altered by intense heat, pressure, or both. The original, unaltered rock is called the 'parent' rock and can be igneous, sedimentary, or metamorphic in origin.

Metamorphism (from the Greek terms 'meta'--to change, and 'morph'--form) can occur in several ways. 'Regional' metamorphism occurs when huge masses of magma are intruded deep within the crust over a wide area. The intrusion often occurs along converging (colliding) or diverging plate boundaries and causes high heat and high pressures. Superheated fluids circulating through rock pores and fractures are also involved in regional metamorphism. The fluids can come from the magma, from groundwater, or perhaps even from sea water entering at the plate boundary. These fluids cause 'metasomatism'--chemical changes in the rocks due to the exchange of elements between the fluids and the heated rocks. Rocks may be so altered that the parent rock cannot be identified.

'Contact' metamorphism occurs over a fairly small area when veins of magma are intruded in the upper crust. Pressures do not increase much, but high heat can cause recrystallization. 'Dynamic,' or 'cataclastic', metamorphism often occurs along faults. The rocks can be ground to a powder or may be altered by sudden high pressures at low temperatures. 'Impact' metamorphism occurs around meteor craters. The sudden impact pressure alters surface minerals producing those usually found only in the lowermost crust. Some useful metamorphic rocks are marble and slate. Profitable metal mines (copper, iron, etc.) are often found in zones of contact metamorphism or along the outer boundaries of regionally metamorphosed rock. Some other common metamorphic rocks are quartzite, micas, schist, and gneiss.