How is this circular motion achieved? heat ‘"pushes" the magma up, and when it hits the lithosphere it is pushed back down towards the core. heated magma is magnetic and is drawn to the lithosphere where it loses its magnetic force and drops back down due to gravity. heated magma rises from the core, but rocks in the asthenosphere block the magma on each side, causing it to move in small circles. hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.