Answer:
Most of the volcanic rock like the plutonic rocks in the north west cascade range.
Step-by-step explanation:
- Most of the lava flows have known to have occurred in these rocks formed under the cascade system of mountains in the Northwest of the united states. Eruptions that have lasted for 4000 years formed by the shields, lava domes, and cinder cones examples of mount rainier.
- Plutonic igneous rocks are thus formed as a result of crystallization of the extrusive igneous rocks due to the magma eruptions on the earth and thy consist of about 7% of the earth's land surface area.