Types of Soil: Soil is classified according to colour, size and texture of soil particles. There are mainly four types of soil:♦ Sandy soil has more sand and no humus.♦ Clayey soil is usually brown in colour. It has more clay than sand particles.♦ Loamy soil is a mixture of clayey soil, sandy soil and […]
Soil: The uppermost thin layer covering the Earth’s surface is called soil. Soil is composed of rock particles, mineral fragments, remains of the dead, living things, water and air. The soil has five layers: humus, topsoil, subsoil, rock fragments and bedrock. There are four basic types of soil: sand, loamy, silt and clayey. Soil Profile:
Petroleum: Petro means rock and oleum means oil. Thus petroleum means rock oil as it is obtained from the Earth (either ocean floor or continental crust). The natural unprocessed form of petroleum is called crude oil. Petroleum was formed from the dead remains of aquatic animals. The bodies of these animals got buried in the
Fossil Fuels: Fossil fuels were formed hundreds of millions of years ago from minerals found in the remains of plants and animals. The process of fossil fuel formation is very slow. They are non-renewable (things that cannot be replaced when used) resources of the Earth. They are categorised into three main types: coal, oil and
Dinosaurs: Dinosaurs mean ‘terrible lizards’. They were one of the most successful species ever to survive on the Earth. They were the well-known reptiles of the Mesozoic era. They ranged from being herbivores, carnivores to omnivores. They were different from early reptiles due to the following features: (1) Dinosaurs had their legs under their bodies.
About 2.6 million years ago, a unit of time named the quaternary period (the current and most recent of the three periods of the Cenozoic era) began. This period has been characterised by a long-term reduction in the temperature of the Earth’s surface or time of glaciation or ice age. During that period, the Earth
Fossil plants are older than fossil animals. They are mostly found as trace fossils in sedimentary rocks of land or freshwater origin. The first plants were related to the blue green algae family and they are probably 2 billion years old. A plant and its parts cannot become a fossil until they are quickly buried
Vertebrates, the animals with backbones, first appeared on the Earth during the Palaeozoic period. Agnathids were the oldest vertebrates which resembled fish. Rocks from late Palaeozoic period revealed 75 different species of amphibians. Most of the fossils resembled today’s salamanders. Body, cast and trace fossils of dinosaurs have been found during exploration. Fossils of the
Invertebrates, the animals without backbones, first appeared on the Earth during the Cambrian period. The most common early animals were arthropods, the trilobites. They were soft-bodies animals living mostly in the sea. Another important fossils of invertebrates found during the Paleozoic time were molluscs, echinoderms, crinoids (sea lilies: cup-shaped body), starfish and corals. Fossils of
The two main categories of fossils are: body fossils and trace fossils. Body fossils are the remains of bones, teeth, shells of an animal, or leaves of a plant. They are further divided into two categories: mould and cast fossil. Trace fossils are just the impressions of an animal or plant created when it was
Fossils: Fossils are the evidence of ancient life. The word fossil is derived from a Latin word fossus, which means ‘having been dug up’. Fossils are the remains or traces of remains of the actual bodies of the organisms, such as bones, shells, feathers and leaves, which have been preserved from decay, and which appear
Diamond is the hardest and purest natural substance known to man till date. Diamonds are made up of carbon. They were formed millions of years ago under the surface of the Earth (more than about 120 km below). Carbon present in the rocks inside the Earth underwent crushing pressure and intense heat. This extreme condition
Gems are the most valuable, durable, beautiful, and rare crystals. There are about 80 known gems. They are divided into two categories: precious and semi-precious. Precious gems include: diamond, ruby, emerald and sapphire. Semi-precious gems include: opal, amethyst and topaz. Most of the gems are made up of combination of a substance called silicate. Diamond
Gold, silver and platinum are precious metals. These metals have low density, higher conductivity, are non-magnetic in nature. They hold a high economic value. Gold is a soft and yellow-coloured metal. It is found in its natural form called ‘nuggets’. Silver, a white-coloured soft metal, occurs in combination with sulphur, copper, lead or arsenic. Platinum
Ferrous minerals are iron-rich minerals. They are less stable and more prone to rapid decomposition than non-ferrous minerals because they are formed under high pressure and temperature. Ferrous minerals usually tend to become dark and heavy. Iron ore, manganese and chromites are the examples of ferrous minerals. India is fairly rich in the deposits of
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