Category Geology

Fossils are the remains of animals or plants which once lived on the Earth millions of years ago. When fossils were first discovered, people did not really understand what they were, and so, many myths and folklore developed over time, about where fossils came from.

            The coiled shell of some fossils led the Ancient Greeks to believe they were related to the ram-god Ammon. In China, these were also thought to resemble horns, and were called ‘horn stones’. In England, they were believed to be coiled snakes that had somehow lost their heads, and turned to stone. Echinoids, also known as sea urchins, are amongst the most commonly found fossils. In some places, they are considered to be snakes’ eggs, which have the power to protect one from deadly poisons.

Fire Eating Dragons

            Over 40,000 years ago, giant bears roamed over Europe. Some of them were buries in caves while hibernating, and over hundreds of years, their bodies turned into fossils with huge canine teeth. When these fossils were discovered in the Middle Ages, they were thought to be the remains of a mythical creature, the fire breathing dragon.

Earth is estimated to be about 4.5 billion years old, hand for much of that history, it has been home to life in one form or another. Today, there are several theories for how life arose on Earth. The first of these is that life was created by a Supreme Being or spiritual force. The second theory is that life began in another part of the Universe, and arrived on Earth by accident when a comet or meteor crashed.

            Scientists say that life began around 3.5 billion years ago as a result of a complex sequence of chemical reactions that took place spontaneously in the Earth’s atmosphere. Molecules were formed as a result of these reactions. The molecules then interacted with one another, and this eventually led to the earliest forms of life.

            The first beings were probably bacteria which survived on naturally occurring food, and did not breathe oxygen. The fossils of these oldest forms of life have been found in Australian rocks dating back 3.5 billion years.

From the beginning of time, human beings have wondered how the Earth came into existence. Different religions have different explanations Scientists claim that a vast, dark, very hot cloud of dust swirled around a newly formed sun. Gradually, the cloud cooled, and the gas began to condense into billions of droplets. Slowly, these droplets were pulled together into clumps by their own gravity – and they carried on clumping until all the planets, including the Earth, were formed. In short, scientists and researchers have been arguing for centuries about how the Earth was formed, and the debate still continues.

The Hadean Period started when the Earth was formed about 4.5 billion years ago. During Hadean times, the Solar System was forming, probably within a large cloud of gas and dust around the sun. The sun was formed within such a cloud of gas and dust. The tendency of matter to clump together finally resulted in the formation of substantial bodies like the planets, and their moons.

            The oldest Earth rocks and Moon rocks we know about both date to this time. Water was brought to Earth by comets that crashed into the Earth. This water boiled into steam, because the Earth was still very hot, and formed a steam atmosphere around the Earth. As the Earth cooled down, about 4.3 billion years ago, the steam in the atmosphere also cooled down, and fell as rain on the Earth, and that made the oceans. By 4.2 billion years ago, Earth had land and oceans.

With reference to the answer that appeared in these columns on Feb 29, a discerning student might very well ask: The centrifugal force is not a real force, so what is the real explanation of tides?

            It is not difficult to explain tides. The question to ask is: Does not the moon’s gravity pull the rest of the earth, which is under the ocean water, towards it as well?

            It does. But the surface directly under the moon is nearer to it than the rest of the earth below, and hence gets pulled more. If this surface is water, being more elastic, it rises in the direction of the moon. The water at the ocean floor ‘remains’ with the earth. The difference between the ocean surface and the floor becomes greater than it normally is. We recognize this as high tide.

            Coming now to the opposite side of the earth, the bulk of the earth is nearer to the moon than the surface here and is pulled more. Water at the ocean floor here is ‘carried along’ with the rest of the earth towards the moon, but water on the surface stays where the lesser pull on it dictates. Again the difference between the surface and the floor increases and we see a high tide. When the moon is at the horizon at right angles to the overhead position the ocean and the earth below it are at roughly the same distance from the moon and experience the same pull. The ocean depth is normal. But, because some of the ocean water has flown to where there is a high tide, there is less water here and we see a low tide. Of course, this is a very simple model and the tides are influenced by many other factors, such as latitude and the shape of the continents.

There are various kinds of methods and they are all based on a method known as “triangulation”. If one knows one side and two angles of any triangle (or two sides and one angle), one can find out the rest of its measurement. Whether the land one wants to measure is a hectare or 1000 hectares, the method of measuring is the same. One begins by measuring one distance very accurately with a chain, steel or wire.

            This now becomes the side of the first triangle and is usually a level piece of ground between two landmarks. Now select a third landmark and make this the apex of the triangle. Then the angle it makes with each end of the first line is measured. These are the requirements for measuring the area of the triangle as described above (one side and two angles of a triangle).

            The instrument for measuring these angles is called a transit; with the area of one triangle the land to be measured into triangles should be divided until the area of the entire piece of land. The transit works vertically which is called leveling as there is a spirit level at the base of the instrument that indicates when it is in level. By raising the sight to any landmark on a mountain, the same process of measuring angles can be done and the length of one side (the height) can be measured.