The way in which each of the three major groups of rocks forms is different

That's correct! The three major groups of rocks, known as igneous, sedimentary, and metamorphic rocks, have distinct formation processes. Let me explain how each group forms:

1. Igneous rocks: Igneous rocks are formed through the solidification of magma or lava. When molten rock, or magma, cools and solidifies within the Earth's crust, it forms intrusive or plutonic igneous rocks. These rocks have large mineral crystals due to slow cooling beneath the Earth's surface. On the other hand, when magma reaches the surface and erupts as lava, it cools quickly and forms extrusive or volcanic igneous rocks. These rocks often have small mineral crystals or glassy textures.

2. Sedimentary rocks: Sedimentary rocks are formed through the process of deposition, compaction, and cementation of sediments. Weathering and erosion break down pre-existing rocks into smaller particles such as sand, silt, and clay. These sediments are then transported by water, wind, or ice to a new location, where they settle and accumulate. Over time, the weight of the overlying sediments and the pressure from compaction cause the sediments to become compacted and solidified into sedimentary rocks. Cementation occurs when minerals are dissolved in water and act as a glue, binding the sediments together.

3. Metamorphic rocks: Metamorphic rocks are formed from pre-existing rocks that undergo changes in their mineralogy and texture due to high heat, pressure, or chemical activity without melting completely. This process typically occurs deep within the Earth's crust, usually in areas of tectonic activity such as where two plates collide or when rocks are buried deep beneath the surface. The intense heat and pressure cause the minerals in the pre-existing rocks to recrystallize, forming new minerals and creating a different rock with unique textures and structures.

To summarize, igneous rocks form from cooling and solidification of magma or lava, sedimentary rocks form through the accumulation and compaction of sediments, and metamorphic rocks form from the alteration of pre-existing rocks through heat and pressure.