Mesozoic Era

Mesozoic era is considered a transitional stage of the development of the planet. Some geologists call it "biological and geological Middle Ages".

The Mesozoic era began after the completion of the Variscian (Variscan) mountain-building processes, and ended with the beginning of the Alpine folding (the major recent tectonic revolution).

In the Southern Hemisphere , the split of the ancient mainland of Gondwana ended. In general, life in the Mesozoic era was relatively calm. The processes of mountain building were rare and short-lived.

The Mesozoic era lasted about 160 million years.

From a biological point of view, this epoch was the time of transition from primitive, old forms to more progressive, new ones. The world at that time was much more diverse than in the Paleozoic, and the flora and fauna were significantly updated.

Mesozoic era. Periods

There are three stages in this era.

The first - Triassic - is named because of the fact that three different rock complexes are included in its sediments. They include the neper - the upper, the limestone - the middle, the continental sandstone - the lower one. The most characteristic are sandy-clay continental rocks (often with carbon lenses), shales, marine limestones, gypsum, salt, lagoon anhydrides.

In the Triassic period, the southern continent (Gondwana) joined the northern continent (Laurasia). Along with these changes in the distribution of land and sea, mountain building, the formation of new volcanic sites, there was a fairly intensive and updating of the plant and animal life. In this case, only a few species migrated from the Paleozoic to Mesozoic. According to the researchers, all these factors are the result of large-scale catastrophes that occurred at the border of the epochs.

The next stage, which includes the Mesozoic Era - Jurassic. It began about 200, and ended about 145.5 million years ago. The Jurassic period has become one of the most famous periods in the development of the planet.

At this time, the most widespread among plants were gymnosperms and ferns. It is assumed that the surrounding conditions were similar to the conditions of the Carboniferous period, since extensive coal formation was noted. The huge continent that existed in the Permian system, which began to split in the Triassic system, continued to decay. This process had a significant impact on the currents in the ocean, the amount of precipitation, the climate and the conditions of existence of organisms in general.

The Jurassic period is considered a "reptile time". The land was inhabited by dinosaurs. In the seas lived plesiosaurs and ichthyosaurs, in the air - pterosaurs. Among the dinosaurs began to form giant species. Along with this, there were small insectivorous pterodactyls. At the end of the Jurassic period, the accumulation of powerful layered layers of limestone - chalk began. Thus, a new stage arose.

The beginning of the Cretaceous period is characterized by some large-scale events in the formation of the organic world. At this time, the first flowering plants began to appear , the fossil remains of which are represented by wood and leaves of the species that grow today (for example, elm, oak, willow, maple). The fauna in the Cretaceous period is basically similar to the one that developed in the Jurassic period.

The end of this stage was characterized by intensive orogenesis (mountain building) in East Asia, North and South America. Sedimentary rocks, accumulated in the Andes Geosyncline for several periods, were compacted and crumpled into folds. Thus, the Andes were formed.

Volcanic activity intensified in many areas of the planet. The entire southern part of the Hindustan Peninsula was covered with lava (thus forming a large plateau "Dean"). At the end of the Mesozoic Era, significant uplifts were recorded on all continents.