Key Differences between Intrusive and Extrusive Rocks

Intrusive Rocks:
- Intrusive rocks are formed beneath the Earth's surface from slowly cooling magma.
- The cooling process allows for the formation of large crystals due to the slow cooling rate.
- Examples of intrusive rocks include granite, diorite, and gabbro.
- These rocks are generally coarse-grained and have a visible crystalline structure.
- Intrusive rocks are often found in mountain ranges and are more common in continental crust.

Extrusive Rocks:
- Extrusive rocks are formed on the Earth's surface from quickly cooling lava.
- The rapid cooling does not allow for the growth of large crystals, resulting in fine-grained rocks.
- Examples of extrusive rocks include basalt, andesite, and rhyolite.
- These rocks are typically dark in color and may have a glassy appearance.
- Extrusive rocks are commonly found in volcanic areas and oceanic crust.

Key Differences:
- Intrusive rocks form from magma beneath the Earth's surface, while extrusive rocks form from lava on the Earth's surface.
- Intrusive rocks have larger crystals due to slow cooling, while extrusive rocks have fine-grained textures due to rapid cooling.
- Intrusive rocks are coarse-grained and often found in mountain ranges, whereas extrusive rocks are fine-grained and found in volcanic areas.
- The cooling rate is the primary factor that differentiates the two types of rocks and determines their physical characteristics.