Main types of rocks

Main types of rocks

Rocks differ in their properties, size and particles and mode of formation. On the basis of mode of formation rocks may be grouped into three types:-

1. Igneous rocks 

2. Sedimentary rocks

3. Metamorphic rocks

Igneous rocks

The word igneous is derived from the Latin word 'ignis' meaning fire. Igneous rocks are formed by the cooling of highly heated molten fluid material, known as Magma. The word Magma is derived from the Greek word which means 'dough'. It requires a greater quantity of heat to melt the rocks under the overlying pressure than at the surface. We do not know the exact depths at which magma forms but probably it is formed at different depths not exceeding 40km.

Sedimentary rocks

These rocks are formed by successive deposition of sediments. These sediments may be the debris eroded from any previously rock material  which may be igneous rock, metamorphic or old sedimentary rock. Sedimentary rocks have layered or stratified structure. The thickness of strata varies from few millimeters to several metres. So these rocks are also called stratified rocks. Generally, these rocks have some type of fossil between  their strata. 

Metamorphic rocks

Most rocks in mountainous regions show an evidence of change. All these in course of time become Metamorphic or changed forms of rocks. Metamorphic rocks are formed under the influence of heat or pressure on sedimentary or igneous rocks. Tremendous pressure and high temprature change the colour, hardness, structure and composition of all types of pre-existing rocks. 

What do you know about

History?

History is the study of the past as it is described in written document. Events occurring before written record are considered prehistory. It is an umbrella term that relate to past events as well as Memory, Discovery, Collection, Organization, Presentation and Interpretation of information about these event. Scholar who wrote about past is called historians. 

What do you know about

political science?

Political Science is the part of social science which deals the foundations of the state and the principles of the government. According to J W Garner,"Politics began and ends with the state". "Similarly, R G Gettell wrote that Politics is the "study of the state in past, present and future". Harold J Laski stated in the same vein that the study of politics concerns itself with the life of men and women in relation to organized state. Thus as a social science, Political science deals with those aspects of individuals in society which relate to their activities and organizations devoted to seeking of power, resolution of conflicts and all these, within an overall framework of the rule and law as laid down by the state. 

Bronze Age

The Bronze Age in the Indian Subcontinent began around 5,300 years ago with the early Indus Valley Civilization (including cities like Harappa, Mohenjodaro, Lothal, Kalibanga). It was centered on the Indus river and its tributaries which extended into the Ghaggar-Hakra river valley, the Ganga-Yamuna Doab, Gujarat, and southeastern Afghanistan. The civilization is mainly in modern day India and Pakistan.

The first cities in the subcontinent were in the first indus valley civilization. It is one of the world's largest and earliest urban civilisations, with Mesopotamia and Ancient Egypt.

Inhabitants of the ancient indus river valley, the Harappans, developed new techniques in metallurgy and handicraft and product like copper, bronze, lead and tin.

During the later period of this civilisation sign of a gradual decline began to emerge. About 3,700 years ago, most of the cities were abandoned. However, the indus valley civilization did not disappear suddenly. Some parts of the indus civilization may have survived in the similar villages and isolated farms.

Geography

What do you know about

Geography?

Geography is the one of the oldest earth science and its roots date back in the works of the early Greek scholars. The word 'geography' was the first used by the Greek scholar Eratosthenes in the third century B.C.

Geo "Earth" and Graphy "to describe" literal meaning of geography is to describe about earth's surfaces. In other words "Geography is largely the study of the interaction of all physical and human and natural activities occur and how these activities are interconnected.

Geography has undergone changes in its approach. The earlier geographers were descriptive geographers. Later, geography came to be developed as an analytical science. Today the discipline is not only concerned with description but also with analysis as well as prediction

In our website you will know how important geography is in our life. This study will encourage you to understand your own place and spaces with greater interest.

Also like our Facebook page:-https://www.facebook.com/higeotics/ 

History of India

The history of India covers thousands of years. It covers many periods and dynasties. It may divided in the following parts. These are:-

1. The Stone Age

2. The Bronze Age 

3. The Vedic Civillization

4. The Persian and Greek Invasion

5. The Magadha Empire

6. Early Middle Kingdoms

7. Late Middle Kingdoms

8. Colonial Era

9. Republic of India

10. Mordern India

For More Details :-http://historygeopolitic.blogspot.in/p/geography.html