Volcanic Glass

There are three types of rocks on earth. They are Igneous, Sedimentary and Metamorphic rocks. Igneous rocks are formed by the solidification of magma and are further divided into two types, Namely, Plutonic rocks(Intrusive igneous rocks) and Volcanic rocks(Extrusive igneous rocks). Plutonic rocks are the rocks that are solidified inside the earth and are usually crystalline in nature due to the slow cooling process Thus they have a coarse grained crystal structure. Volcanic rocks however solidify muck quicker and therefore often show a very fine grained crystal structure. If the cooling and solidification of the volcanic rocks happen even faster it leaves no time for crystal formation. This makes the volcanic rocks amorphous and therefore have properties of a supercooled liquid. That is, These rocks have a glassy texture and are brittle like glass. They also exhibit a conchoidal fracture just like glass. One such rock is Obsidian. Obisidian looks almost artificial and has a remarkable appearance. They are sometimes used to fashion precision cutting tools such as surgical knives. Obsidian has such an appearance that it is hard to believe that it actually is a rock and that it is formed naturally.. It looks artificial. It is a remarkable product of Earth's natural geology. Here's a picture of Obsidian.

Hard to believe..

Here's an interesting problem. Suppose you take an extremely long ribbon and wrap it tightly around the Earth-along the equator, the distance being about 40000km. Imagine that the earth is smooth and that there no space whatsoever beneath the ribbon. Now suppose you lengthen the ribbon by 1meter. This would cause the ribbon to slack and will leave a gap from the surface of the earth to the ribbon. (look at the diagram)

How big is this gap? (Indicated by the arrow on the diagram)
Any guesses?
Well its roughly 16 centimeters. This is an interesting result many people find hard to believe. But a simple calculation will show you that it's true.
Here's the math,

For the initial case ,
c=pi*d
where
c- circumference of the earth and thus the initial length of the ribbon.
d- diameter of the earth
c1=c+1
c1-new length of the ribbon(after lengthening by 1 meter)
c1=pi*(d+2*x)
x- gap between earth and the ribbon(indicated by the arrow)
therefore,
pi*d+1=pi*d+2*pi*x
x=1/2*pi=0.159m
which is approximately equal to 16 centimeters.

Environmental Engineering

Environmental Engineering was formerly known as Sanitation Engineering and was a subdivision of Civil Engineering. As many new engineering fields, it developed into main engineering stream as its demand and complexity increased. Today it is an vital and interdisciplinary field incorporating many areas such as, Chemistry, Fluid mechanics, Hydrology, Geology and Ecology. Environmental Engineering is mainly concerned with improving public health while protecting nature.
While traditional Engineering focuses on merely utilizing resources and improving living conditions of humans, environmental engineering incorporates the conservation of nature and promoting the well being of humans and other living species in the environment as well. This approach brings out sustainability and overall development.
The key areas of environmental engineering could be identified as,
1. Providing palatable and safe public water supplies in adequate amounts.
2. Control and implement procedures to minimize water soil atmospheric and noise pollution.
3. Recycling waste where possible and proper treatment and disposal of solid and liquid wastes.
4. Implementing procedures to minimize the overall footprint.
5. Incorporating cleaner production mechanisms to protect the environment and to increase sustainability and efficiency of industries.
Environmental engineering is still an emerging field in developing countries and needs to be given immediate consideration because the efficient use and management of the earth's resources will aid development and help to sustain it.