The sequence of deposition of sediments, the mountain building events and evolution of plants and animals are major factors that provide data for compiling the geological history of the earth which is divided into FOUR major eras:

1.Pre-Cambrain Era: (600 to 3300 million yews)
During this era, the earth evolved from its original state when it became a separate planetary body. This era ends at a point when life became abundant and diversified. The formation of continents on the surface may have commenced rather early. The atmosphere and water of the earth was essentially in their present state by the end of the era.

2. Paleozoic Era: (230 to 600 million years)
An era of ancient life. The early paleozoic was generally quiet, with volcanism and mountain building activity at a low ebb. The early paleozoic was an age of marine vertebrates. All the major phyla were in existence and the seas were teaming with life. The first land vegetation appeared in this period. The interval closed with an intense mountain building movement (Caledonian) in north-west Europe and lie continents became relatively higher. Signs of glacial action have been found in Africa, Australia, South America and India. This feature and similarity in fossil forms (remains of dead animals and plants) and igneous activity, is considered by many geologists to indicate that, all southern continents were then joined in one super land mass called the Gondwana Land. The late paleozoic was a time of evolution and expansion of land life. Amphibians and reptiles appeared in this era.

3. Mesozoic Era: (63 to 230 million years)
An era of middle life. The drifting apart of the continents of the Gondwana Land is supposed to have occurred during this era. Mesozoic life was in transition. Plants became better adjusted to dry land environment and to seasonal changes. On land reptiles represented by the dinosaurs were dominant vertebrates. Mammals and birds appeared in this era.

4. Cenozoic Era: (Recent times to 63 million years)
This era pertains to present life. Mammals were the dominant form of land life. Birds and fishes continued to evolve in their respective environments and became highly specialized. Plants migrated widely. Grass became the dominant vegetative form in temperate regions. Many raw materials came into existence, oil, gas and coal were formed and many deposits of metallic minerals were formed in association with igneous activity.

During the last million years the climate of the earth has been such that glacial accumulated over at least 27 % of the land. The ice age caused great disturbance in the organic world. Plants and animals were forced to migrate with changing climates and there was an overall reduction in the organic productivity of the land. There was noticeable extermination specially amongst the larger mammals, but the greatest extinction seems to have occurred after the last glaciation was over. These adjustments were a sort of prelude to the appearance of man which was a climatic event in (the history of the earth. Man had appeared somewhere in the interglacial periods.

This division of the geological history of the earth into FOUR eras, is not haphazard or at random but is based on breaks in the sequence of deposition of sediments – the physical discordance known as unconfirmities. These four geological eras, arranged in what is called the Geological Time Scale, are universally accepted as a basis for worldwide correlation.

The FOUR geological eras indicate the development of life, (i.e. plants and animals which are food for higher organism), drifting of continents, mountain building activity etc. The Quran also states that the provision of food, i.e. creation of plants and animals and making of mountains was completed in FOUR periods. Is the mention of Four periods in the Quran, for provision of food and making of mountains just a coincidence or a 1400 year old confirmation of the findings of the geologists?