Question

Why are California's mountains and alleys generally parallel to the coast?

Answer 1

The Pacific Ocean Plate created a subduction zone pushing up the mountains parallel to the ocean.

Explanation:

The Sierra Nevada mountains are granite the result of magma pushing up from the crack in the earth created by the subduction zone where the Pacific Ocean Plate pushed under the Continental Plate of North America.

The mountains are parallel to the coast because the ocean plate pushed in from the coast. The costal ranges were created in the same way.

The alleys are not a geological feature. California runs north and south. Most roads are laid out north and south so the alleys run north and south parallel to the coast.