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Monthly archives: December, 2021

Mechanics of Intrusion

Source of Magma:  Magma is originated from the upper mantle, which lies just under the crust, and is nearly molten. A slight drop in pressure caused by dee faulting etc, completes the melting process. The basaltic magma originates in this manner, while the “granitic magma” can be produced in two ways: (a) from melting of …

Forms of Igneous Bodies

The igneous material is of two types; one is extrusive, and the other is intrusive. The extrusive igneous bodies are formed from the magma poured out at the surface of the earth. The lava flows are examples of extrusive igneous material. While the igneous bodies are formed by the consolidation of magma at some depth …

Structures of Igneous Rocks

Once the molten magma extrudes out, it is affected by several factors. These factors provide varied structures to the rocks on cooling. Some important factors are as under; (1). Flow Structures: Sometimes an igneous rock shows parallel or subparallel bands or streaks which are caused by the flow of magma or lava during cooling and …