3.2 Notes How are igneous rocks formed? Objective: Identify two ways that igneous rocks are formed Molten rock is formed by melted minerals. When molten rock cools, it becomes solid, forming igneous rock. The temperature of the upper mantle is hot enough to melt minerals to form molten rock. Igneous means “formed by fire.” Why are rocks formed from magma called igneous? Molten rock inside Earth is called magma. Magma is found inside Earth’s upper mantle and lower crust. Magma rises through cracks in Earth’s crust then cools and crystallizes. Magma hardens to form igneous rocks on Earth’s surface. Crust 10C at 300m Mantle 1,000C at 60km Outer core 2,200C at 3,000km Inner core 5,000C at 4,000km Is this a fast process? Magma cools inside Earth’s crust to form large bodies of igneous rock. A general name for all of these bodies of igneous rock is pluton. The types of pluton are: batholiths, stocks, laccoliths, dikes and sills. What is magma? Magma that reaches Earth’s surface is called lava. Lava cools upon contact with air or water. Igneous rocks form quickly from lava. How does lava rise to Earth’s surface?